I am having a similar problem. I just "repaired" my windows XP installation due to a ntldr missing error. After the install it hung on actually getting to the logon window. Hard restart, then when I log in normally it warns me that I must immediatly register it otherwise I cannot log on. So I agree and login. Then nothing. I see my wallpaper and a curser. No icons, no start bar, no right click, and no ctrl-alt-del option. I see that the hard drive is doing something but I have no control.
If I start in safe mode everything looks the way it did previous to the "repair", except for the fact that I cant register in safe mode. Any help or advice would be very appriciated.