|IF you still have a problem after that, run Memtest86 (create bootable CD from downloaded ISO image and boot to it). Run through all tests. ANY errors means you have a bad stick of memory, retest with one stick at a time, replace as needed or replace matched pair.|
If both show no problems and the trouble still exists then try a system restore to a date before you began having trouble.
You have to be a little bit crazy to keep you from going insane.