After installing the OTA Android 4.2 upgrade onto my nexus 7 without rooted and unlocked, now it keep rebooting itself, even in safe mode. I just have a day of usual use. I am also experiencing that the apps crash and keyboard doesn't go away from screen. I try to do a hard reset and it still randomly reboot very 30 seconds on its own. This doesn't happened on 4.1. How to fix the issues?
There is a general 4.2 problem. You need to do a system hard reset.
* Shut down the tablet and connect it to computer.
* Press Volume Up + Volume Down + Power to power it up, then select the Recovery Mode option. Use volume button to go to "Wipe Data / Factory Reset" and do that.
* Another way is to go to Setting, switch off WiFi and connect network again. That also seems to fix it.