turning off evo problems.

[jmdesv]

just today I have been unable to get my evo 4g to turn on when its been sleeping. the phone will still be on and the only way I know it didn't die was when I plugged it in the screen came on. when the screen is on I try to hit the button on top of the phone to either put it to sleep or turn it off, but nothing happens. I did take the battery out once and pushed the power button and the phone came on...I am totally clueless to what is causing this. afraid to let it go to sleep on its own after timing out, because I am afraid at some point it won't let me turn it back on. any help is much appreciated. thanks!