Unplug it. Read HP's noted on how to clean it out. Follow the directions as if it is a fresh new install.
In closing I just had to do this on a friend's machine after they whacked the machine with a registry cleaner. Gad why do they use those things?
When i try to scan the scanner says i need software if i push the button or when i try to use acrobat reader hpqscnvw.exe has stopped working error comes up I have reloaded software and tried everything i know to sort it bur to no avail Vista and hp are infuriating Please help it was working fine last week and now its packed up