Try a cache partition wipe, which only erases temporary system data that might be messing things up (no important personal data will be lost). This can especially be a problem if you've recently done a system update. Here are the steps:
- If your tablet is on, power it off.
- Press and hold Power until the device powers on, then immediately press and hold Volume Down (while still pressing Power). You will see the word Start with an arrow drawn around it.
- Press Volume Down twice to designate Recovery mode.
- Press Power to restart into Recovery mode. You will see an image of an Android robot with a red exclamation mark.
- While holding down Power, press Volume Up.
- Use the volume keys to scroll to "wipe cache partition" and press Power to select it.
- When done, select "reboot system now" and press Power to execute.