I had constant reboots on every rom after unlocking the bootloader and/or installing cwm recovery. I tried official update.app and left everything else and the reboots have gone completely. Then I just unlocked the loader and the reboots started again but I wanted to use CWM 10.1 so it's okay :)
Right now I'm using llama to automatically switch to 2g when the screen goes black and switch back to 3g when the screen turns back on. It's stable since then and I can live with that setup. I'm still eager to try relocking the bootloader though, to get rid of that extra app.