Loading ImageList from resources fails in long test run

[NewDawn]

I have a test project with about 1200 unit tests. Whenever I run them all,
after about half way through the tests, the loading of image lists from
resources fails. Here is the line of code and the exception that is thrown:

this._headerExpandImages.ImageStream =
((System.Windows.Forms.ImageListStreamer)(resources.GetObject("_headerExpandImages.ImageStream")));

System.Reflection.TargetInvocationException: Exception has been thrown by
the target of an invocation. ---> System.InvalidOperationException: Loading
of the ImageList did not succeed..

I can only reproduce this when all of the tests are run. If I run the same
tests alone or in smaller groups, there are no problems.

Part of this problem might be linked to another problem I've had with this
same project with a large number of tests. By the time the tests are done
running, the VSTestHost.exe process has over 500 MB of memory allocated to
it. This causes a problem for some of our machines that only have 1GB of ram
in them as much time is spent swapping page files and I often get
OutOfMemoryExceptions.