Hello Vger,
Can you boot it to safe mode?
You can get to safe mode by repeatedly hitting F8 during bootup until you get the boot options screen. When it comes up, choose safe mode and see what happens.
When it goes to a black screen, does it just sit at the black screen, or does it restart the computer and do it all over again?
Worst case scenario is you can't get safe mode to work. What you can do then is take the hard driver out, attach it to another computer, and try to get the important data off that way.
Let me know what you come up with and we will go from there.
