Who knew a computer clock could lose time?

At 2 pm I had 4 browers open so that I could listen to Rachmaninoff and do other things without using tabs and for some reason that I can't remember I clicked on Ad Aware to scan for problems. Next thing you know it is 10.00 pm and Windows 7 is checking to see why the computer clock is 10 minutes slow. I went to bed and left it checking for problems. I have now updated Firefox and I'm crossing my fingers.