Clearing your system cache partition may potentially solve your problem while ensuring that no personal data will be lost. The system cache partition is a storage area for system data such as logfiles, frequently accessed app data that is temporarily cached there, and downloaded apk (Android Package) installer files from Google Play. Over time, temporary data can build up and cause system delay or malfunction.
In order to clear the cache partition, you need to access the device’s Recovery Menu:
1. Power your tablet down
2. Now press and hold Power
3. When the Google logo appears, while still holding Power, press and hold Volume Down until the Start screen appears.
4. Now use the Volume keys to select Recovery (press Volume Down twice) and then press Power.
5. While pressing and holding Power, press the Volume Up button and then release both buttons.
6. You should now see the Recovery Menu. Now use the Volume buttons to highlight “wipe cache partition” (press Volume Down three times) and then press Power.
7. The Recovery Menu should appear with “reboot system now” highlighted.
8. Press the Power button and your tablet will reboot.
If you experience any other problems please visit the Nexus 7 (2nd gen) troubleshooting page