Laptop won't start!

I've searched every where for a similar problem so I could be pointed to a solution, but with no luck. I'll describe my problem now.

I have an HP ProBook 4540s, running on Windows 7. It's been with me for a good over two years now. Five days ago my sister told me while she was using it, it gave her a blue error screen and then shut down. Days later of attempting to turn it on, with no luck.

This is exactly what it does: power button immediately turns it on, fan is running, nothing on the keyboard is flashing- like usual. The blue hp logo shows up, and it takes very long for that to disappear, and when it does I'm met with a black screen for a few minutes before it goes onto the 'windows is loading files' screen, then the Microsoft corporation screen for one second, and after another black screen I'm met with a blank login screen plus a rather big cursor. Nothing happens after that, and the only option is to shut down- which it easily does.

I can't use safe mode, as the only keys that do work once I turn on my laptop are the control+alt+delete combo which just goes back to the same hp logo screen over and over, control+esc which then prompts me to press f8 if I have Windows 7 highlighted (nothing happens, just another black screen) or the memory diagnostic, which says there are no problems. Since I'm going to be back from break in a few days and have a chance to get repairs, I just wanted to know if there was anything I could do. I can't bear a reset, and would prefer answers as soon as possible..