I have the exact same problem, which I posted in a separate thread some time ago. The general consensus was that my SIM was faulty, so about a month ago, I got a new one. Worked nicely for a few days, but then I started having the same problem on and off, moreso within the last 2 weeks. My data also rarely works, though T-mo customer service said that might just be an issue associated with the new SIM activation? Additionally, I have issues charging from all types of sources (battery indicator and charging light comes on, but after a few seconds, it stops charging and I need to keep pulling the battery until it decides to charge for real). I do have the same power on issue that you have. A reflashing might fix these problems, but I'm too lazy, so I'm waiting for the new firmware to come out first. :P