Vista - Screen turns off - in one account

The oddest thing has happened to my computer: the screen turns off when I log
into my account. After I input my password, my settings load and I glimpse
my background, the toolbar and my icons, and then the screen shuts down. The
computer still runs, however. When started up in safe mode the screen stays
on, and the guest account and the other account have no problems when started
normally. There is no problem when starting the computer.

I'm using Vista Home Premium, the account in question is an administrative
account, and I don't think I've downloaded or updated anything recently.

Any suggestions?