TP 6.0, NT Workstation and didappearing mouse

Hi everybody,
I've just installed TP 6.0 on a machine working with NT Workstation.
(I used it before with win 95 without trouble)
With NT Wstation, I run TP6.0 without problem, that is to say with the mouse,
But, as soon as I compile and run a pascal application and go back to editing,
the mouse is gone...?!
The only way is to leave TP and run it again !

What is the problem ?