User Profile Service problem

When I turned on my other laptop (Sony VGNAR520E) yesterday, a message came up on the screen that a Windows Update was in progress and I should not shut down. I did nothing at all to the computer--just watched while the download progressed. When the download finished and the computer restarted, a screen that was not "mine" appeared, with a minimum number of icons on a black background, and just a few icons on the task bar. Wanting to use one of my programs, I decided to reboot to see if my personal preferences would load. When I restarted, a screen appeared wth the Windows 7 Ultimate background and this message: "The User Profile Services service failed the logon. User profile cannot be loaded." Below that was an "Okay" button. When I click on the OKAY button, the background remains the same, but in the center is my "Pat" avatar, and in the lower right hand corner there is a Shut Down icon. Now when I shut down and/or restart, the word "Welcome" flashes on the screen very briefly, but is immediately replaced by the message about the User Profile Services failure. I have tried many times to restart, but have never again seen the "black" screen, or anything else. Unfortunately, I have failed to back up my files. Is there any way I can fix this problem? Incidentally, I doubt that it matters, but that computer originally had the Vista OS, but two or three years ago, my son-in-law replaced it with Windows 7. I've gotten several Windows updates, but never had any problems until now.

I sure hope you can help me! Thanks for your attention.

Thanks so very, very much! The System Restore worked! I had to try it twice, but it did eventually work and I am REALLY GRATEFUL. Sincerely, Pat Naber