Pulseaudio uses a good chunk of CPU when you are playing music, there are a few threads on maemo that discuss this - your phone will heat up as a result. If you find your phone locking up and not wanting to start again, what works for me is simply to remove the battery briefly, insert, and then hit the power again. Also you can just persevere with holding the power button down - seems like the 3rd press can sometimes bring it back to life - though all of this is subjective, it might just be that there is some process or function running for a short while that needs to die, reset, or activate... YMMV. : ) A good idea is to make use of your xterm and use the command "top" to see what might be eating up your CPU. You can then kill the process if it seems abnormal.