Monitor goes blank after startup

[weigh144]

I have an older PC with XP home. It starts up fine with the XP logo and the progress bar showing fine. When the computer goes to the homepage the screen goes blank. The light on the monitor is green and the computer seems to be working fine. I only say that because the lights on the tower are blinking as they always have.
My son was messing with some settings and I'm afraid he may have messed something up there. I could probably figure this out if I could see what I was doing.

Any suggestions?

 

[Tmagic650]

See if you can get into the Safe Mode by pressing F8 repeatedly as the computer begins to boot. Once in Safe Mode get into the device manager and look for any yellow exclamation points. You may be able to delete the video driver in there and get the computer to re-install the driver correctly on a restart. This is a video driver issue brought on by your son messing with the video resolution