Repro:
1) In a Mono region, rez a vehicle for which you have permission to recompile scripts, and recompile it's scripts to Mono.
2) Drive the vehicle across a region boundary into a Second Life Server region.
3) Stand Up from the vehicle.
Results:
Your avatar can not fully navigate, because the controls permissions have not been returned. The Mono vehicle cannot return controls after it has entered a SL Server region due to it's bytecode not being recognized.
You need to relog or use another means to restore avatar controls, such as an overrider or another vehicle.
Expected results:
The controls should be returned/released upon entering the Second Life server region, or returned upon dismount.