My computer is refusing to recognize my password after waking up from hibernation. It works fine after Standby, Logoff, and Reboot. I'm 100% positive I'm entering the right password. It seems to be erratic -- it's worked on a few tests, but failed most of them (rebooting is the only fix I've found). I think this is a recent development (I noticed it just after applying the most recent security updates) but I don't use Hibernate often so it could have been around for a while.

Any clues?