Urgent help needed!

I turn on the computer, wait for the boot screen to load, and 10 minutes later, I’m still on the boot screen. The little progress bar just keeps going and going, and it never stops.

I unplug the PC from the wall, plug it back in, and let it restart. Same result.

I unplug it again, but this time I have the option of Safe Mode. I log in, and try to do a System Restore to an earlier date, with no success. Then go back in Safe Mode, and do a virus scan, and my PC is clean.

I try to restart again, and all I get is the boot screen.

Now I’m in Safe Mode with Networking, and I desperately need to get back in to normal Windows.

I have a Sony VAIO PCV-W510G
2.4 GHZ
Windows XP SP2
512 MB RAM