Have you tried this:
Go into Settings, Application Manager (or Manage Apps), All Apps, then scroll to Camera and click on it.
From there click on Clear Data.
This will reset the settings for the camera and hopefully get it working again.
OR Try this:
Firstly,
Update your tablet to latest version of Android.
This can be done -via OTA by - going to
Settings--> About device--> Software update.
via
Kies by connecting your device to your computer and allowing the software suite to update your tablet.
If your tablet's OS is updated.
Then try killing all the applications by long pressing the home button,
and going to task manager tab to kill all processes.
Good luck with it.
Signed: Ensign Tzap