HELP - Blackberry Curve 9360 - Random Restart/Reboot

I have a Blackberry Curve 9360 and it keeps randomly restarting/rebooting. I have wiped the phone and put new firmware v7 on there still did not work so I even wiped it again and put Firmware v6 just in case it was not compatible. Next I tried swapping the battery with a friend the phone still kept rebooting. The reboot normally happens with a few minutes from getting onto the home screen. Next I tryed swapping the Sim Card I was using a GiffGaff sim so I then put in a Tesco Mobile sim in and it worked it has only rebooted 3/4 times but takes around a hour before reboot from start up. The phone is unlocked, When I had the GiffGaff Sim in it worked for about a week before the random restart/reboots started.

I want to keep using the GiffGaff sim but I just do not see why it will not work any ideas?

Could be either a software or hardware problem. Sounds like a glitch to me, the OS telling the hardware to power off.

How would I fix a glitch? I have formatted the whole phone to the point where there is not a single file on there and tryed lots of firmwares still no luck and why would it just do it with one sim card?

I have had a similar issue with Curve 9370 (Verizon). I have searched the forums and followed all suggestions. Now phone has Error 102. I have given up with attempting to get this one to work. First started with random shutdown/restart then started booting up with jvm errors. Latest was a java error. I wiped clean and reloaded operating system. now, I cannot even choose a different version of OS and cannot complete a restore as I have backed up and restored many times.