Using Taskmgr.exe is not a good way to gauge .NET program memory usage. When you minimize an app's main window, the Windows memory manager aggressively trims the program's working set, unmapping as many memory pages from RAM as it can. That means nothing for actual memory usage, the program's virtual memory size doesn't change. This is most certainly not something you want to do intentionally, it just makes the program very slow when it has to wait for pages getting mapped back into RAM again.
You only have a real problem when virtual memory size grows without bound. Getting window creation exceptions indicates that you are leaking handles. That's fairly easy to do, removing controls from a form and not calling Dispose() for them for example. Graphics.CopyFromScreen() had a handle leak, fixed in .NET 3.5 SP1. Use SysInternals' ProcExp utility to get some insight in what code in your app is causing the leak.
Hans Passant.
You only have a real problem when virtual memory size grows without bound. Getting window creation exceptions indicates that you are leaking handles. That's fairly easy to do, removing controls from a form and not calling Dispose() for them for example. Graphics.CopyFromScreen() had a handle leak, fixed in .NET 3.5 SP1. Use SysInternals' ProcExp utility to get some insight in what code in your app is causing the leak.
Hans Passant.