Hi Aerror. I saw another thread today where several people were having a similar problem but no solution.
Try pulling the battery and leaving it out a few minutes then restart.
Try some compressed air and blowing around the power and volume buttons.
I don't know if it will help, and if it does you will have to reinstall all your apps, but you can try a factory reset in recovery. If you don't know how,
Power off your phone again. Hold both volume buttons and the power button at the same time. When the phone vibrates, let go of the power button but keep holding both volume buttons. In a few seconds you should be in the recovery menu. Use volume buttons to move up/down and power button to select. *if power button doesn't work, use your home key*. Go to wipe data/factory reset and select it. Next, select format cache partition. Now select reboot.