I am trying to repair my sister laptop Asus x51rl.The laptop rebooted 2 min after logging in and the dvd drive didn't work. I noticed that it was full of viruses after checking processes in task manager. I tried to install xp from a usb stick but it showed a blue error screen when it tried to start windows. I succesfully installed and booted Ubuntu 9.10 trying to see if it was a hardware problem. Tried to install xp again, no luck. I checked memory with memtest86+ all ok, updated BIOS from 203 to 204, the latest for this laptop, and succesfully installed xp by putting the harddisk in my computer but when i put it back it show the "blue death screen" and reboots immediatly after the win logo appears.I forgot to mention that I ran CHKDSK with the hardrive on my computer and all I got to see was " 4 KB in bad sectors". Can anyone help? I don't know what to do.