As I've mentioned on another thread I'm having an issue where my taskbar is persistent and it never hides even on the start screen and using Metro UI apps. I know the cause of it but I don't know if it's isolated or it affects all Windows 8.1 tablets. Please try going to System --> Advanced System Settings --> Advanced --> Performance Settings --> Disable "Animate windows when Minimizing and Maximizing." After that see if your taskbar becauses persistent and answer my poll. Don't worry if you re-enable the setting the taskbar will start working properly again. I can't leave it enabled because it's not compatible with Citrix Receiver client which I use for work.