windows xp sp2 will not shutdown or restart

[exodusprime1337]

So i've been having a very odd error ever since i went from vista back to xp sp2. I cannot restart or shutdown my computer at all. it is not an intermittent error or and it doesn't shut down slowly. It simply returns to a black screen after the "saving your settings" prompt. I've tried registry tweaks, disabling startup items, and disabling fast user switching, and the welcome screen as well. nothing seems to work at all. I never had this problem before vista, now it seems i have this problem all the time. the computer pretty much just stops all activity like it should just before the pc should actually power off but the screen just goes black instead and it sits there?? is there anything that i can do to stop this??

[exodusprime1337]

i guess nobody has had this problem or knows what to do lol. crap i'm screwed, just reinstalled windows and not only does it hang during shutdown from desktop, it hangs during the restarts while it's installing windows. somebody please help me