The system cannot log you on now because domain <name> is ont available

All of a sudden, after my cat pulled the plug out from my computer, I am getting prompted for a password to log on when I never had one before. No matter what is or isn't entered into the password box, the following message comes up, "The system cannot log you on now because the domain LYNN is not available." I tried all the things you were supposed to do before running hijack this and maybe because I'm running in safe mode, I couldn't install any of the programs and Bitdefender won't run, says it's missing a dll file. I am running Win XP service pack 3 and am not and have never been part of a domain. I am networked with another computer in the house via a linksys router.

At some point, prior to this happening, I ended up with a popup telling me my computer was not running well and I should run their check. Of course, I didn't and just closed all the pop ups, but I wonder now if something did download. As I said, I'm in safe mode, so can't do a whole lot. I've also tried running the win disk that came with the computer (Dell, preloaded with windows) and it just hangs if you try to reinstall windows. HELP!!!!!!!!!!