System restore is restoring the registry...........for 5 hours (and counting!)

I have vista home premium and i used the windows system restore to undo
windows updates (which included a rather annoying ie8) the initial restore
claimed to have failed and i was given the option to undo the restore, which
i did... to my cost it seems. now i can't do anything with the laptop, no
keys seem to be working and i have even tried to get the task manager up with
no avail. I'm scared to turn the damn thing off incase i lose everything! any
ideas?