This is actually indication of a stuck power button.
Couple things I'd suggest:
Make sure there's no lint stuck in the button that can hold it down.If you can take it apart, I'd try that and clean it. Some users have reported that makes it as good as new.
Are you rooted? If you are, you can always remap the keys (navigate to /system/usr/keylayout/) and you can put a # to disbale the power button, and change the volume up key to say POWER instead.
Hope that helps!