Desktop screen is black but i see bkgrd imgs

My desktop has a black screen after it has booted all of the way up. You can still make out programs running in the back ground and click stuff with the mouse (just barely) its just extremely dark. Both the monitor and the tower have blue lights like they are running properly i just cant see anything. i do see my norton antivirus pop up whenever i log in and i am able to right click the screen to get the properties box up so i am at a loss as to what this could be??

Thanks for any help,
It is a windows xp sp2, hp
not sure which firefox version i have on it. i just need to get it running to retrieve some files.