I have intel dual core processor,4 gb of ram,ATI 6770 hd graphics card and windows 8 64 bit OS. When I leave my computer for a while(I mean not making any movement by mouse or keyboard) a blue screen flashes and it shows "YOUR COMPUTER RAN INTO AN ERROR" and then restarts and after restarting it can't detect my Hard Disk.This problem didn't occur at beginning when I installed Windows 8 but I didn't use my PC for about 6 months and when I started using it again this problem occurred.I installed latest windows updates but the results are still the same.Another one, when I open task manager it shows disk usage 100% and my PC is running slower than usual I closed every application running in background but it didn't change anything.