In Windows 7, I've had the experience (twice) of logging in, only to be told that I have been given a temporary profile. Once, the temporary profile stuck - I couldn't get back to my own Profile, even though my entire Users folder was still intact but "locked" (whatever that means). I made a copy of it, created a new Admin account, deleted my original account, rebooted, logged into the new Admin account, created a new account to replace my original one, and copied the contents of my original Users folder back into the new Users folder. What a pain - and I'm not sure everything was recovered - some of my desktop icons were gone for good.
I would love to see a way to snapshot my profile when I shut down, and then be able to recover it completely in case something like this happens again. It took me a couple of days to get back most of my email, shortcuts and settings in various programs.
