How to solve automatic logging off problem?

I have 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 a 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. All help is greatly appreciated, thank you.
