It's acting weird....

Okay, I have this problem, and I'll be damned if I can track it down to what is causing it...
Basicly, if I have more than say 3 or 4 programs running and I try to adjust the volume on my computer (either throhg the icon up top, the keys, system preferences, doesn't matter), my computer logs me out for no **** reason! It is realy starting to **** me off and I don't quite know what it causing it, or how to make it stop.

If anyone has seen this please let me know. It is starting to drive me nuts!!!!

All that comes to my mind is that your system runs out of memory (that may explain why it happens when running 3 applications or more), why don't you try activating the virtual memory (if it isn't already active), or increasing the virtual memory.