Here we go.

I'm working on a HP laptop running Windows Vista Home Premium 64b. When I boot into Normal Mode, the OS has trouble running anything that would seemingly need a Secondary Logon, for instance running an app as admin, or for instance even trying to access the Network and Sharing Center. It locks up Explorer and the system just doesn't want to operate. However when you boot into Safe Mode w/ Networking, everything functions properly. So this lead me to think the system may be viral. Alas the system is perfectly clean. Running utils revealed no infections whatsoever. So then I had the bright idea to cold boot the system. This ultimately p***ed off Vista to the point where it's now asking me to input the product key on the COA. Well that's fine and dandy but when you input the PK and click the Next button, which is an action that requires elevation implying the Secondary Logon service, the system cuts to the busy cursor and that's it.

Any bright ideas as to the cause of this and a resolution short of a nuke and reinstall would be greatly appreciated.

EDIT: Could this possibly be the cause of a rootkit? I really don't think so but I could be wrong.