Computer is an old Dell Dimension, Windows xp home. It was on your average surge protector power strip, power outage occurred overnight and then when they tried to turn on the computer in the morning windows starts to load but then there is just a black screen with "lsass.exe application error failed to initialize properly" error (safe mode too). Screen will stay there indefinitely after you click ok on error. Last known good config doesn't work. So, tried to boot to windows disk to repair lsass error but then get "ntldr is missing error". Happens trying to boot to usb as well. Checked bios boot sequence/device settings. Thinking maybe a controller issue or something with the MB due to the improper shutdown/power outage but don't want to just miss something obvious/easy that I should try. Assistance much appreciated.