Hey MDL, It all started when I installed SP1. I downloaded it from TPB, so it was probably a virus. Cause I couldn't acces the internet. So I put in my Original Windows 7 CD. The setup started, I choose "Custom Installation". The setup started, but after a while a square popped up, saying "Windows cannot install required files. The file does not exist. Make sure all files required for the installation are available, and restart the intstallation. Error code: 0x80070002". I turned of the computer. When I turned it on again, "Startup Repair" launched. When it had finnished scanned it sayed "Startup Repair could not detect the problem". Now, what am I supose to do? When I try to boot from a CD or USB device, I press F12, choose either a USB device or a CD. But there is just a flashing arrow in the upper-left corner of the screen. HELP?