A hard reset is the same as a factory data reset. When you did the reset, did the tablet immediately start reinstalling all of your apps? If so, then the problem might be due to some app that keeps reinstalling. Try uninstalling all apps, and see if the problem persists. Or try booting into Safe Mode. You can usually get to Safe Mode by pressing and holding Power until the Power dialog box comes up. Then press and hold Power Off until a Safe Mode prompt comes up. Tap Ok, and the tablet should reboot into Safe Mode, which disables all 3rd party apps. If the problem persists, then there's something wrong with the firmware. If the problem goes away, then something you installed is constantly causing problems.
Also, consider removing any SD card, since a corrupt card can cause issues.