I had the same problem on my Galaxy Tab 2 (rooted). I think it happened after I tried Link2SD.
Any way the solution was to download and enter "Terminal Emulator", execute 'su', execute "pm set-install-location 0". This sets it up as 'auto'. It was set to '2' (external).
I believe the problem is that the GT2 has an internal 'SDCard' and an external "extSDCard" and there is some kind of confusion between them in the OS (4.1.1 Ice Creme Sandwich)
OMG you are awesome. This fixed my problem. Your the best.