I have a machine that is my friends, needed a simple cleaning up. I scanned the hard drive with avast and removed the viruses from an external hard drive setup. I then restored the hard drive to the computer and started it up receiving this message: Windows could not start because the following file is missing or corrupt:; <Windows root>\system32\hal.dll Please re-install a copy of the above file I have looked this up and found this link for a solution http://support.microsoft.com/kb/314477 I have not had much experience with repairing windows, and the last time I tried doing such a thing, the hard drive got overwritten and all the information was wiped somehow. The information on the hard drive is critical, so I need to know if backing up the data is recommended. Do things go wrong with a repair normally? I cant have anything go wrong on this, so I need the best recommendation on what to do.