How it will be solved automatic logging off problem?

I am facing a problem with my PC. My Windows XP boots up as usual to the log on screen. As soon as I impute my password, Windows plays the log on sound and then just automatically log me off again. I have had many attempts to try and get windows to stay running including booting from CD and repair but unsuccessful.
I don’t know what I should do now. I tried to run my pc in safe mode (F8 method), but I didn’t get any result. I am planning on getting a new PC soon, but need access to my user account as there are many important documents for my work.
