Windows 7 Profile Loss

I have a new Dell Latitude E5400 came with XP Pro installed with Windows 7 upgrade CD. I installed Windows 7 and it seemed to work fine for two weeks. Just yesterday I powered down the laptop and when I restarted it had lost all profile info. I was able to log in but it started as if it were a totally new profile.

I was able to retrieve some documents from previous versions of the profile but the same thing happened again and I’m now dealing with a new profile.

Any ideas?