"Low on space" message on an android tablet I just got a Agptek 9" tablet.  It's running android 4.04, ICS with 8GB storage and 512MB of RAM.  It generally runs great.  After a few days the tablet is getting a "low on space" error message in the notification bar.

In the storage area of settings, it shows over 800MB not used.  Because of this error, it will not allow downloads, including updates and the tablet very runs slow. All downloaded apps have been moved to the SD card.  All cache has been removed.   

The only software in the internal storage is android files and apps that came with the tablet, which can not be moved or removed.  Yet, the notification bar shows "low on space".  I did a "factory data reset" and the problem was resolved for a while.  But, the problem shorty returns.  

Can you give me assistance in how to fix this.  Or steer me in the right direction for help.
Even if you move apps to the SDcard, the apps will still use space in /data/data/ this is where the user data is stored for the application. this includes things like the database, additional application specific files, other cached data. 

Devices that do not have large a /data/data partition are very troublesome with a lot of current applications. Applications like Google+, Chrome, Gmail (just as a couple examples) can use a lot of space in /data/data/.

To see if the issue is /data/data/ you can try and clear Data for some applications and see if the notification goes away. Not just the cache for the application, actually clearing the data.