First I Would Check The Cables To The Monitor To See If Something Is Loose.
Did You Try Playing With The Monitor Settings?
Go To Control Panel Or Front Monitor See If There Is A Solution There.
See If You Can Test Your Video Card Hardware And Driver Updates.
Next I Would Start Pricing A New Monitor.
Running Windows Vista Home Premium 32-bit. Whenever I close any windows, be it searching the WEB or playing a game, my desktops fades a bit like dimming light, then a couple seconds later does it again. Any ideas on what to do?