Try resetting your cmos, you do this by removing the battery from you mobo and holding the power button for 15 seconds, then plug the round battery back into the motherboard and start the computer again.
"If your motherboard does not have a CLEAR CMOS jumper, you can often clear its CMOS settings by removing the CMOS battery and replacing it. The CMOS battery provides power used to save the BIOS settings – this is how your computer knows how much time has passed even when it’s been powered-off for a while – so removing the battery will remove the source of power and clear the settings.
Important Note: Not all motherboards have removable CMOS batteries. If the battery won’t come loose, don’t force it.
First, ensure the computer is powered off and you’re grounded so you won’t damage the motherboard with static electricity. Locate the round, flat, silver battery on the motherboard and carefully remove it. Wait five minutes before reseating the battery."
-Taken from www.howtogeek.com