No new instances of anything in Windows XP!

I've had this problem pop up every so often for the past month or so.  My computer won't acknowledge any new instances.  I'll right click my mouse, and no menu will pop up.  I'll try to open a folder or a program, and nothing happens.  CLTR+ALT+DELETE doesn't do anything.  When this is happening, some programs of mine will shut down if I try right clicking in them, most notably IRC.

So far I haven't noticed anything that would set it off, it's seemingly random.  Has anyone ever heard of this before?  I've tried googling, but to no avail.  Help please!

Something I forgot to mention, whenever I close a program during this time, I can open up new instances for a short amount of time, then I go back to not being able to.  IE, can't get right click menu, I close out a folder, and I can right click menu for a few seconds before I can't again.

Reinstall Gentoo.

but then i wouldn't be able to play all of my favorite gaaames.

you have a virus or most likely a rootkit, if you can, backup all your stuff and reinstall. (use ubcd4win or a linux live cd to access your data and backup)