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Application runs out of Memory despite garbage collection and only 10mB RAM usage C# Windows Forms

I try coding an Application that shows a slideshow with a picture box.
Loading a new image causes the application to run out of memory at some point. Even though i dispose the old images and manualy run GC. Task Explorer shows 10mB usage.
At first i saw the ram increase withouth the dispose function. Including the dispose kept the ram constant but still throws the out of memory exception at some point.
My code to load the next image and dispose the old one.
I needed to include the Application.DoEvents() because the UI Thread did not get updated
PictureBox.Image.Dispose();
PictureBox.Image = Image.FromFile(currentfolder.ImageList[currentindex]);
Application.DoEvents();
currentindex++;
GC.Collect();
I cannot see any reason why i run out of memory. My System has 8GB and is running 57% usage at idle.

Thanks a lot. The Problem actually was that i had elements in the list that were no images. The out of Memory Exception really confused me.
Thanks steve16351 and the others

WinRT how expensive is reading from local file cache

I am building a winrt metro app and always seem to run into this (non?) issue.
I find myself maintaining a lot of files of cached data that I can serialize back and forth. Data retrieved from services, user selected items and so on.
The question that I always seem to have when I write the calls is: is it the accessing of the actual file (and releasing etc) that takes time/is expensive or the amount of data that needs to be serialized from it?
How much should I worry about, for example, trying to combine a couple of files that may have the same object types stored into one and then identifying the ones I need once I have the objects 'out'.

Did you ever get insufficient Memory or memory out of bounds exception.
Winrt lets you use the ram and the cached file upto around 70-80% of its memory . Any thing beyond that will crash the app. Once you navigate away fro your page your resorces are garbage collected so thats not an issue. But if you are using using for the memory stream then also it will be fine but saving large data and continiously fetching files from the data base effects system memory. And since surface tablets have limited memory set so should take a bit care about large number of files :) i faced this while rendering bitmaps as loading around 100 bitmaps simultaneously into the memory threw insufficient memory exception.

How to manually release resources from images downloaded via the web in WP7?

Hi I'm bringing back some items from a web service that contains three strings. One of those is the path to an image. Now when I start loading the images into a listbox the memory as expected starts to go up which isn't bad. But when I hit the back button the memory is still very high.
I'm thinking it has to do with the fact that I'm not releasing the resources taken up by the images. The idea comes from this answer => Question.
Does anyone know how to manually release these resources?

There's no Dispose() method for Image or BitmapImage classes, so the best you can do is dispose the stream you're getting the data to. But I'd personally look for the problem somewhere else since Images should be GC'd automatically (in fact, they do).
There might be event handlers that bind to your page from outside making GC unable to collect it, e.g. you have a reference to the page in your application settings or something. Or the GC just doesn't at once collect the dumped objects but waits for the specific time - try moving back/forward several times and see if the memory raises up and up and up.
Anyway, there's no need/ability to free resources taken by Image/BitmapImage manually (only the corresponding Stream, which usually doesn't give the result since it's cached in the image).

.net memory measuring and profiling

I understand there are many questions related to this, so I'll be very specific.
I create Console application with two instructions. Create a List with some large capacity and fill it with sample data, and then clear that List or make it equal to null.
What I want to know is if there is a way for me to know/measure/profile while debugging or not, if the actual memory used by the application after the list was cleared and null-ed is about the same as before the list was created and populated. I know for sure that the application has disposed of the information and the GC has finished collecting, but can I know for sure how much memory my application would consume after this?
I understand that during the process of filling the list, a lot of memory is allocated and after it's been cleared that memory may become available to other process if it needs it, but is it possible to measure the real memory consumed by the application at the end?
Thanks
Edit: OK, here is my real scenario and objective. I work on a WPF application that works with large amounts of data read through USB device. At some point, the application allocates about 700+ MB of memory to store all the List data, which it parses, analyzes and then writes to the filesystem. When I write the data to the filesystem, I clear all the Lists and dispose all collections that previously held the large data, so I can do another data processing. I want to know that I won't run into performance issues or eventually use up all memory. I'm fine with my program using a lot of memory, but I'm not fine with it using it all after few USB processings.
How can I go around controlling this? Are memory or process profilers used in case like this? Simply using Task Manager, I see my application taking up 800 MB of memory, but after I clear the collections, the memory stays the same. I understand this won't go down unless windows needs it, so I was wondering if I can know for sure that the memory is cleared and free to be used (by my application or windows)

It is very hard to measure "real memory" usage on Windows if you mean physical memory. Most likley you want something else like:
Amount of memory allocated for the process (see Zooba's answer)
Amount of Managed memory allocated - CLR Profiler, or any other profiler listed in this one - Best .NET memory and performance profiler?
What Task Manager reports for your application
Note that it is not necessary that after garbage collection is finished amount of memory allocated for your process (1) changes - GC may keep allocated memory for future managed allocations (this behavior is not specific to CLR for memory allcation - most memory allocators keep free blocks for later usage unless forced to release it by some means). The http://blogs.msdn.com/b/maoni/ blog is excelent source for details on GC/memory.

Process Explorer will give you all the information you need. Specifically, you will probably be most interested in the "private bytes history" graph for your process.
Alternatively, it is possible to use Window's Performance Monitor to track your specific application. This should give identical information to Process Explorer, though it will let you write the actual numbers out to a separate file.
(A picture because I can...)

I personaly use SciTech Memory Profiler
It has a real time option that you can use to see your memory usage. It has help me find a number of problems with leaking memory.

Try ANTS Profiler. Its not free but you can try the trial version.
http://www.red-gate.com/products/dotnet-development/ants-performance-profiler/

System.OutOfMemory being thrown. How to find the culprit?

I am using Visual C# Express 2008 and I have an application that starts up on a form, but uses a thread with a delegated display function to take care of essentially all the processing. That way my form doesn't lock up while tasks are being processed.
Semi-recently, after going through a repeated process a number of times (the program processes incoming data, so when data comes in, the process repeats) my app will crash with a System.OutOfMemory error.
The stack trace in the error message is useless because it only directs me to the the line where I call the delegated form control function.
I've heard people say they use ProcMon from SysInternals to see why errors like this happen. But I, for the life of me, can't figure it out. The amount of memory I am using doesn't change as the program runs, if it goes up, it comes back down. Plus, even if it was going up, how do I figure out which part of my program is the problem?
How can I go about investigating this problem?
EDIT:
So, after delving further into this issue, I looked through anything that I was ever re-declaring. There were a few instances where I had hugematrix = new uint[gigantic], so I got rid of about 3 of those.
Instead of getting rid of the error, it is now far more obscured and confusing.
My application takes the incoming data, and renders it using OpenGL. Now, instead of throwing "System.OutOfMemory" it simply does not render anything with OpenGL.
The only difference in my code is that I do not make new matrices for holding the data I plot. That way, I hope, my array stays in the same place in memory and doesn't do anything suicidal to my LOH.
Unfortunately, this twists the beast far beyond my meager means. With zero errors popping up, and all my data structures apparently still properly filled, how can I find my problem? Does OpenGL use memory in an obscure way so as to not throw exceptions when it fails? Is memory still a problem? How do I find out? All the memory profilers in the world seem to tell me very little.
EDIT:
With the boatloads of support from this community (with extra kudos to Amissico) the error has finally been rooted out. Apparently I was adding items to an OpenGL list, and never taking them off the list.
The app that finally clued me in was .Net Memory Profiler. At the time of crash it showed 1.5GB of data in the <unknown> category. Through process of elimination (everything else in the list that was named), the last thing to be checked off the list was the OpenGL rendering pipleline. The rest is history.

Based on the description in your comments, I would suspect that you are either not disposing of your images correctly or that you have severe Large Object Heap fragmentation and, when trying to allocate for a new image, don't have enough contiguous space available. See this question for more info - Large Object Heap Fragmentation

You need to use a memory profiler, such as the ants memory profiler to find out what causes this error.
Are you re-registering an event handler on every loop and not un-registering it?

CLR Profiler for the .NET Framework 2.0 at https://github.com/MicrosoftArchive/clrprofiler
The most common cause of memory fragmentation is excessive string creation.

Following considerations:
Make sure that threads you spawn are destroyed (aborted or function return). Too much threads can fail application, although in Task Manager used memory is not too high
Memory leaks. Yes, yes, you can cause them in .net pretty well without setting reference to nulls. This can be solved by using memory profilers like dotTrace or ANTS Memory Profiler

I had an OutOfMemoryException-problem as well:
Microsoft Visual C# 2008 Reducing number of loaded dlls
The reason was fragmentation of 2GB GB virtual address space and poster nobugz suggested Sysinternal's Vmmap utility which has been very helpful for diagnostics. You can use it to check if your free memory areas become more fragmented over time. (First sort by size then by type -> refresh repeat sorting and you can see if contiguous free memory blocks become smaller)