Nexus 7 randomly reboots and resets date to 1999
I have N7 too. I never heard or read about anything like this. It can be faulty battery or charging circuit, but it can be just SW problem.

First, please, add some important details to your question:


Did you use original charger?
Did you use original USB cable?
Did you use original dock?
What android version do you have?
Do you have this version out of box from the first day (from factory) or did you get it as OTA update or did you update it yourself?
How many apps do you have installed?
Do you use any task killer?
Did you try reset to factory defaults?