Your computer may be in the middle of "automatic updates"? Maybe some kind of "automated scan" in progress (virus...malware programs).

You could type "msinfo32" at the run command and look at "hardware resources" "Memory" to make sure your vid mem says OK.

Hit Ctrl+Alt+Del and look at the "processes tab" and llok at the Mem Usage column to see if you can pinpoint what is hogging Memory (Would this show for a process using "Vid mem Michael?)

Restart your computer.

Theres a start.