Try wiping the cache partition following these instructions:

1. Reboot your tablet into the bootloader by turning it off, and then pushing the volume down + power buttons at the same time. Keep them down until you see the bootloader screen.
2. Then, use your volume buttons until you see Recovery displayed, and press the power button to select.
3. If you’re on a stock recovery, wait until you see the Android with the red exclamation point, and press volume up + power at the same time and keep them down until you see the Recovery menu.
4. Use the volume keys to select the option to clear your tablet’s cache, then press the power button to execute.

If this doesn't help, you should consider a factory reset, although this means reinstalling all of your apps.