Rebooting Issue

Hello

My Nighthawk MR2100 is rebooting when the battery is not in the device. It does not happen all the time, but I usually have to load the battery into the device for a day or so and then it can boot sucessfully without the battery wihtout rebooting over and over again. Has this happended with other Nighthark MR 2100's. I've tried it in both charge only and charge and tether modes without success. 

Thanks for any help/info