No desktop or anything

My daughter has Compaq computer with Windows XP home- last night I installed AVG Free and ran a complete scan. It (AVG) ran for 6 hours and found 48 viruses and trojan horses before I went to bed. When I got up, it said "program not responding" so I cussed a little (ok, alot) and clicked shut down now. Well, that shut down the whole computer and now I get nothing. I have tried the F8 button (holding it down, tapping it, and even just clicking once) but it still goes to "windows is starting" or something like that. I can get to the log in screen but when I click it, all I get is the wallpaper- no desktop, no start button, no task bar, nothing. After maybe 30 seconds, it says "Logging off" and goes back to the log in screen. Is there anything I can do or did I mess up her computer completely? Any help would be GREATLY appreciated!!!
Oh yeah, I didn't get to finish running AVG- didn't get to remove the viruses and trojan horses.

 

I should add that I am on her laptop now- I can't download anything to help her desktop.