System Low on virtual memory+freezing, applications not working,

Ok, so my first build, specs in my sig.
Also have a HD 4890 coming in soon...

The problem I'm getting is all the sudden I started getting "Low on virtual memory" errors, and then the system would freeze. Went into Computer Management properties and increased virtual memory size.... No more error messages, but it still freezes. When it does not freeze, apps like Firefox will not even open, although the exe is running in task manager, and KMPlayer will not open any DVD or file.

Also, when logged in, computer will not restart or shut down by itself.

Safe mode so far has not given me any problems, other than FF won't open, shut down/restart problems.

And of course, when I boot into Ubuntu nothing goes wrong.... however the school that I go to requires Clean Access Agent to go online, and of course Linux can't run CCA. This is pretty urgent because I have two term papers due pretty soon.

Any help would be much appreciated.