I also cut my sim card to make it into a micro sim. I new this was possible but thought this might be a bad idea but when I spoke to vodafone about getting a new sim, they said 'bring it in and we'll cut it down for you'. I thought I might as well do it myself.
I just had a thought. How many of you with the rebooting problem have their phones in cases? Mine is. Now that you can't remove the battery to reset they've built that functionality into the power off button. Hold down to reset. I don't think it's that sensitive, but it just got me to thinking, is the case putting some minor pressure on that button to reset the phone? I just tried it manually, and it replicates the reboot... Going to try leaving mine out of the case for a while. Should only take a day to find out. Having said that, it does it sat on the desk on charge without having been touched.