Default [Q] No buttons when rotating the tablet to the side after 4.3 upgrade

Hi all,
upgraded my tablet to 4.3 with the Sony PC program. Now when I rotate the tablet to the side the three buttons disappear.
I did a repair, flashed 4.2.2 and then upgraded again, and after speaking to the Sony teck support did an update from the Sony webpage. Nothing helped.

any idea???