I had the same problem but i have a DELL, i could not work out why suddenly the right side of the screen was all dark, then i thought the lightnings gone, then i thought its not the screen as all the pixels are still working behind it, so then i went to the older problem that when i was a kid it was common problem the power lead/cable, that is plugged into the back of the monitor, the fuse might of gone or something to do with the power not going right into the screen happened a lot 18 years ago but this is less common recently, so the power cable is not working right and thus creating a problem with the monitor just like when a power supply is old and is just hanging in there to keep your pc running while you upgrade parts inside the pc it will cut of so i changed the cable that powers the screen and it worked no more dark side, i can not explain why this happens, but ide suggest its a old problem with power leads or cables pluged in to what ever devise has to work right anyway thats how i got mine to fix simple get a new lead just that plug it in and turn it on i hope it was of help.