Spontaneous user account reset, all data gone

I've just received a call from a panicked friend saying her Windows 7 has reset everything. When she turned it on she got the "preparing your desktop" dialog, the icons are just the default ones with hers gone, and the user document directories are empty. The user account does still have her name, so it has been reset - Windows isn't just loading another one. She tried a restore point from three days ago and it changed nothing.

I'll get the computer later today and I foresee profanity in abundance. The absolute priority is to recover the user data, then I'll probably do a reinstall just to be sure.

I haven't had this happen before, so I'm uncertain. Why would Windows just up and reset the user account, and is the data recoverable at all if the folders are all empty? I've told her to stop using it and I plan to see if FreeUndelete can salvage some stuff, but as this is the result of a total user account reset and not just an accidental deletion I have little hope that it'll actually do much of anything.

Any advice, beyond yet again stressing the importance of backups?

Hi Same has just happen to my computer using windows 7. Point to note system back ups have gone and its telling me there is no OS which is strange however, all the data is still there in the computer somewhere its just the desktop, internet setting and emails which have been reset, I tried a system restore and that did not work however, I have again gone into the system restore setting and there is now more options to restore to where before there was only one restore point, will let you know how it goes. It did not go well now have a black screen but AVG is working again so going for a system scan. It looks like an update is to blame as we have more than one computer running windows 7 and its only the hp computer which has reset, there was an critical update at 09:30 (ish). Well it looks like a day of red bull for me trying to fix the dam thing

Been playing with the recycle bin as it is full (ish) did a restore of one item that had been deleted from the desktop days ago and it worked it moved out of the bin and onto the desktop however, not onto the desktop it is showing me now but the old desktop which I can't find anywhere

Found the desktop and all other files. my computer, c drive, user folder, user name. And all the files are there (or should be).

Try to fix the profile. You receive a "The User Profile Service failed the logon? error message

I got the laptop. Strangely, the profile was only halfway reset. Some applications were still on the desktop, others weren't. The background was black. Any changes would get undone at the next reboot.

I eventually found a profile directory with all the data in there, so that's taken care of. As for the system itself, I'm wiping everything and doing a fresh install.