Thanks for your reply. I've run chkdsk recently and everything in the filesystem was ok, but I ran it again yesterday exactly as you suggested and it did not find any problems. I am currently running a full malwarebytes scan again to see when it stops. Yesterday when I ran it, it stopped after 7 hours and 11 minutes rather than the 7 59 which I had been getting. You are right I do not really have to run a full scan, but running this scan once a week at night doesn't cost me anything and when it used to complete I would also update the definitions. But even if I do not have to do it, I would still like to be able to have Malwarbytes complete a full scan. And it is a mystery to me why it doesn't complete. My C drive has about 238 gigabyte of files to work through. Thanks again for your help.