Hey! you sound like a god of computers.... your post provided me with more information than I needed and half I don't understand. I've got a problem if you can take a few moments and shed some knowledge or instruction as I need to get information that is important to me for september (studies):) Problem: pci.sys file is missing or corrupt. i receive two (2) blue messages: one is the above and the other is a detailed darker blue error message that quickly shuts down the computer - only to do the same. the pci.sys file missing or corrupt occurs only when i insert my windows xp (home edition) CD into the drive for repair or to delete the existing windows xp and apply a fresh copy. if the disk is not in during a regular bootup the detailed darker blue message appears and quickly reboots to "protect your system from damage". the only option i know is F8, which nothing works, and F1 (BIOS) which nothing has worked for me either. i've been reading about creating a streamlined disk....is this the answer for my software (windows xp home ed. with SP2)? what do you think? what is answer here? your time is greatly appreciated.