My Aunt's Dell Inspiron 1525 was booted up today with a problem, it restarts directly after the Windows Vista loading screen (black screen with a bar going to the right in the middle) as soon as that finishes loading it restarts, I've tried safe mode, and tried changing it to booting thoroughly, no change, I'm reluctant to reinstalling Vista onto it because they don't want to lose their pictures and music, any help?

forgotten detail just before the computer initiates an automatic reboot it flashes a blue screen, too fast for me to even see anything aside from blue and white text

Ok I used the f8 and disabled automatic restart on failure and I can read the blue screen now, it says

UNMOUNTABLE_BOOT_VOLUME

so what do I do?