CRASH!!!!!!

here's a problem been buggin me for a year... i put a
desk top pic up... i got the them goin and my computer
after 2-48 hours will flicker.. make a skid noise.. the
blue edges go high contrast black/white and the screen
defaults to the bliss green grass pic... the music effect
stays the same.. i'm assuming this is a mini crash..
none of my other data has been affected.. any clues??
I'm runing xp pro on a micron millenia 1000mhz
thunderbird any body heard of this happening?? i bought
the plus pack for the nice desktops and its a moot
point.. they don't stay up for more than a day or two
before this happens.

CRASH!!!!!!