Did you ever find out what was wrong?
Mine is blacking out too. It has happened when i hit the (red phone key) to put it to sleep. I can hit menu and it won't come back on.
The last time it just shut down but the keys on the bottom of the phone still light up so I know its working just the screen didn't come back up. Then when i do get it to work it was on a different page then the home page. So i know by me touching the Black screen it was activated just not visable.
Very frustrating to be locked out.
Thankfully if I wait long enough i can use it again with no problems. But why should I have to wait a couple minutes to use my phone.