Booting problems

Hey this may actually be a hardware problem but I'm not sure what happening here. Starting a week ago I haven't been able to log into windows at all. Everything starts fine but as soon as I get through the XP loading screen sleep maode apears on the screen and shuts down. I've tried safe mode and I've tried the use last working windows configuration. It still keeps happening.

Now just so everyone knows this started when we were having electrical in the house and power went out several times during boot up. I don't know if this is the problem or not. But I thought I'd include it just in case. If anyone could help that would be great. I can't really afford a new computer right now and need it for school. Thanks

boot off your xp cd and do a repair

Ok... sorry this is taking so long to reply but I have been super busy this week. So I don't have a windows disk of my own. I have a image disk or whatever that came with the computer but I think I'll lose everything on my harddrive if I go that route. Also I don't know where the cmos battery is to try that. I don't want to go ripping things out either. I'm going to try and find a disk from a friend or something (this should be ok if I'm only using it to repair windows right?) Thanks for the help... is there anything I can do in the meantime?

Removing the battery allows clearing of date, time, and (system setup) parameter memories in CMOS, by erasing the RTC RAM data. The onboard button cell battery powers the RAM data in CMOS, including system setup information.