"it starts as normal,but only the backround comes up"
Eeerr..what do you mean that it starts as normal then? DOes the post screen come up and not the welcome page then login? Or does it go through all 3 of the above then go to black screen? Is the curser flashing in the top right hand corner?
"and stays that way for ages there are no files or anything" For ages? So what happens next? Do you re-boot or does it shut down?
Could you provide a few more details please! DOes it see the hard disk? Do you get a message re the operating system?