You'll have to go into the BIOS on your system.
When you boot up you'll see a message saying something like "to enter setup press" followed by the key (usually DEL or one of the function keys).
When you see the message tap the key mentioned until you enter the BIOS (usually a blue screen with menu's and options).
There should be at least 1 option to load setup defaults, sometimes there's 2, if there is choose the minimum or basic default setup.
Save changes and exit.
Hopefully when you reboot the problem will be resolved.