It's not the MoBo, graphics chips on the MoBo, the BIOS, or the drivers. There is a circuit on the top back of the display that drives the rows and colums on the display. Part of the circuit or connection to the screen has gone bad. You an buy a new or aftermarket screen for around $80 or less. It comes assembled with the CCFL lamp and circuit, outside shell not included (it's not needed and costs extra). You just have to carefully plug in a ribbon cable. The lower-priced display is likely an aftermarket item with one or two bad pixels (dark or bright), which should be no more than a minor annoyance at times, unless you view a lot of movies or do a lot of graphics work (but you might want a large external hi-res monitor for those applications). I have the same symptoms on a Dell 21" monitor two years out of warranty. I also had a black screen on a Dell portable computer that was over a year out of warranty. It was easy to fix by swapping out the display assembly. Note: Black screens may be due to a break in the wires that passes through the hinge, or possibly a loose connector attached to those wires. Don't attempt to open your computer or make repairs if it's under warranty, unless you don't mind voiding your warranty. And don't let HP tech support give you the run-around and waste your time. They don't know everything, and HP doesn't want to spend money fixing anything under warranty.