I don't use Windows, and I have a hard time understanding why you want to deiconify the $mw just to destroy it. Your script destroys the $mw fine on linux, with Perl 5.8.8 and the latest Tk. I am not sure why, but I have noticed in the past, that $mw->deiconify() often needs to be used in conjunction with $mw->raise.

On linux, if I comment out your $mw->destroy(), to see if control returns after the system, the $mw will NOT deiconify, and the system command just seems to hang ( which is the problem you are seeing? ).

But, if I put a raise after the deiconify, control returns.

$mw->deiconify;
$mw->raise
[download]

So try adding a $mw->raise and see if it helps.