almost sure its a virus cannot start up pc in safe mode or normal mode using a laptop dell inspiron 1720 have access to dos command prompt and have been able to copy windos registry editor to usb key. but cant seem to run avast or any exe files from usb key. have also tried to intall dos 6 to run avast . no luck. have used system restore in windows setup restored to previous point but not started have access to c and usb ports also drive x do not know how to run program from drives via dos repair dosent work either. running diagnostics error message comes up 2000-0146 almost sure its a virus not a hard drive failure

According to the Dell help section this error means "DST Log contains previous error(s)." DST meaning Drive Self Test. From this it would seem the hard disk has failed or been damaged. If its in warranty, give Dell a call, even if its not in warranty, they seem to be very helpful. http://support.dell.com/support/top... Scroll down until you see your error code. Computers... designed to entertain,help with work but most of all to frustrate you!