Windows Vista [Computer boots to white screen - only the cursor visible]

I have a gateway laptop running windows vista home premium. I restarted it earlier, and it started up normally. It showed the gateway logo, then the vista logo, and then acted like it was taking me to my desktop, at which point the entire screen went white (no wallpaper, no start button, NOTHING!) with the exception of my cursor? Please help, I have online classes tomorrow and I NEED my computer!!!