So here is the info that I have so far:
The computer was on all night because it failed to go to sleep properly. It was also very hot in the morning. This is not irregular for the machine (it's a laptop). Restarted, and the diskcheck started automatically, and I left. Came back some time later and only a black screen with the mouse was visible.
Had to do a hard-power-off, restarted, got to safe-mode, and safe mode didn't load. the last file safe-mode loaded was crcdisk.sys (don't know if this is what it's supposed to do) and then it gave the same black screen with a mouse.
Notes: Vista version is Premium and automatic updates are on. When trying to load Vista not in safe mode, the splash is not visible, but the ribbon underneath is. Also, after loading, I left it standing and it seemed to go into screensaver mode: that is the mouse disappeared. When I moved the mouse again, it came back.
Anyone have any ideas of what I can do?