Windows Explorer & Computer Issues

Hey everyone, I've got a problem with my computer, and I'm pretty sure it's not hardware related, so I hope I'm right posting it here. If this isn't the correct place to put this, sorry, please feel free to move it to where it belongs.

Anyway, here's my problem:

I just got internet back a yesterday, and since I have the only desktop in the house, my step-dad asked me if we could use it as a family computer for a while until we got another one. Well, about 8 hours after hooking it up to the net, it started having a weird issue where windows explorer would need to reboot. Well, shortly after that problem started, it escalated into where my normal log in name won't even work anymore, and when I try to log into it the screen goes black and windows explorer refuses to even boot up (trying to start it through task manager makes it boot for a split second before it closes again) and this DrWatson thing keeps popping up and closing anything I try to run while on that name. I was able to start another name but this Data Execution prompt keeps popping up trying to close windows explorer, so I have to drag it to the bottom of the screen as I go about my business and use the internet. Anyway, I updated my anti-virus software before I let the family use it as a family computer (I use panda anti-virus 2008) and when I ran a scan no viruses were found. When I tried to run a system rollback, I found that windows blocked me out of doing that by closing the "Help and Support" service that comes with windows. I also can't log onto the administrator account in safe mode, because whenever I try to reboot in safe mode my computer restarts.

Sorry for the wall of text, but if anyone can help me figure out the problem that is occurring and how to fix it, please let me know.

Thanks if you can help, if you can't, then thanks anyway for reading.

Jam it back in, in the dark.

Crap... Those are my only two options?

Do you know if there's a way to get the information off of my other name? It just black screens until I windows key+L to logout then goes back to the select user name screen. I obviously can't transfer files to my external from there, and there's a few files I NEED from that name that I won't be able to just download.

Well, thank you very much for the information, I'll need to do that later tonight. Thanks again!

There's nowhere I can't reach.

I'm running XP sp2 right now. Would upgrading to XP sp3 or Vista fix the problem? Sorry about all the questions, but this is the first time I've experienced a problem like this before.

This thing is sticky, and I don't like it. I don't appreciate it.

Ahhh, k. Thanks for all your help Zergrinch!

I am a dolphin, do you want me on your body?