All in One Computer

I have a customer who brought me there all in one computer.As to where everything is built in the back mount of the stand.The problem that they are having is the system will boot but you can’t see anything on the screen when it goes through it’s processes.I can barely see the windows desktop when it boots up.the screen works fine when it’s going through the POST screen but after that you can’t see anything.There is a button that you can push that will let you do a restore of the setting and when i do the screen pops on for about a couple of seconds and you can see the desktop as it should be but it goes right back black after that.Any ideas as to what would cause this problem would greatly be appreciated.

Regards
Eric Moody