Sounds like a virus... let me gess: fast internet connection, download a lot of rubble from all over the place , go figure...
Thats A (a sayes that somthing else is happely eating on your 512ram and letting vb even have the crums)
So, dont run counter strike and vb at the same time unless you know what you are doing.
Now B is a bit more horrible, vb is not designed to run with the new ram?!
You may also try: Ctrl+Alt+Del > higlight DarwinBots > Back click > Go to prosses > Backclick on the prosses > Set Priority > High
Btw, what virsion of the program are you running?