So when I got home from work on Saturday, my computer had a black screen with a Microsoft Update logo at the bottom right of the screen, saying something about an error updating. When I restarted, the computer would not load windows. I got a message stating: "The following file is missing or corrupt: System32\Drivers\Ntfs.sys" So I put in my system recovery disk to repair the file, pressed F10 at the startup screen to load system recovery, and it would not load the recovery interface, saying: "The following file is missing or corrupt: acpi.sys" though sometimes it says iaStor.sys is the corrupt file when trying to load system recovery. I don't know if a virus deleted a bunch of system files, or if my hard drive is bad or what. I had a few "blocked intrusion attempts" on my comp a few weeks ago, and updated my Norton Antivirus definitions last week, and a scan on Friday showed no viruses. I don't know if that is related or not. Any advice on how to fix the problem without reformatting my hard drive would be very appreciated. I have Windows XP, and an HP Pavilion a820n.