I just tried stopping a Z3 proof by clicking the appropriate button on a Windows machine (so the prover is run under Cygwin), and it worked fine.
I've looked in the log in .metada. After clicking the button to terminate the proof, a message is
appended to the log saying that "kill" has been sent to tlapm and then the system
just gets stucked.
Maybe it's only a question of process management.
Anway I will send you a file tomorrow.
--
FL