When I try to run disk defrag on my C drive nothing will happen. Disk defrag will open but will not start the defrag process. I can run scandisk with no problems. Also if you goto properties on the C drive you will get EXPLORER caused an invalid page fault in module Shell32.dll at 015f:6686521b. I ran a current anti-virus check and both spy-bot and adware with negative results. Any one have a clue.