Hi guys, I have an issue with my Hero where the mobile network keeps switching off and says "SIM Unavailable". I have to keep switching the phone on/off to re-enter the my PIN and make calls. I checked all mobile settings and phone settings and can't find anything that would cause this to happen. I generally keep my mobile internet on all the time and WiFi and when at home it switches to my WiFi network. I am still on the original ROM that came with the phone from unboxing. Any help appreciated.