i think the problem is caused because of Overclock. i notice that i cant do overclock on CM10, i dont now why, but a simple 100mhz OC will cause reboot after some minutes/hours. i have mobile data always on and not a single reboot if processor is on standard values.
edit: i missed the part that you have not reboots lool.
I've had random reboots when I was on 3G long before I overclocked.