That's a shame your power button's sleeping on the job. The button isn't physically broken is it? I have a few suggestions if it's not. Have you already tried giving the phone a restart? Sometimes if the phone isn't powered off and on every once in a while it can have some strange behavior like this. You should also try to wipe cache and see if that helps. Please keep us posted. Thanks!
Just stopping by to see if you had a chance to try the wipe cache using the link in my previous post. Please let us know if you still need help. Thanks you!