Windows 7 will not open new processes after running for a while

This is by far the most difficult to pin down problem with Windows I have ever encountered. After letting Windows run for a while without shutting it down (average of two days) it will refuse to open any new processes. Any processes already open will continue to function normally, but nothing new can be launched. Not even by more esoteric methods, like a program that opens a web browser link, or a debugging session in Visual Studio. This issue has been for the most part livable, because it still allows me to save what I am working on before I have to restart. But there is one aspect that has become unacceptable. I can't shut down the computer properly when this bug occurs, because Windows apparently needs to launch a new process to shut itself down. Always having to shut down Windows with a hard reset has started to cause disk corruption issues, and although I haven't lost anything I didn't have a fairly recent backup of yet, I'm starting to worry the disk corruption could be causing other unrelated problems to creep up due to corrupted configuration data.

I really, really hate reinstalling Windows, because it always takes me weeks to get everything the way I like it, with all my setting and installed programs. But I have almost nothing to go on with this issue. I don't remember exactly when it started, or what I had recently installed on the system at the time. Windows is giving me absolutely nothing useful in the error logs. And I can't capture any information on the problem while it's going on, because that would require me to start a new process, which is the one thing I can't do. My only possible hint is an issue I'm having with Windows Media Playing, which may be completely unrelated. I posted a bit on it here, and I was even able to narrow it down to a certain extent. But nothing that would explain why it was happening, or how it might be related to the current state of my OS.

At this point, any help that could be offered would be appreciated. I will probably reinstall Windows by the end of the month if I can't get this sorted out, but I'd really prefer to wait until SP1 comes out. In my experience Service Packs tend to have less installation issues on a fresh copy of Windows that one that's been in service for even a few months.