Are you launching your Tk script via a double-click of the filename in
windows explorer/desktop etc? If so, the script will run and when finished
(or errors occurred) the cmd shell window will disappear, this is normal
Either add a the line: '<STDIN>;' (without quotes) to the end of your
program or run the script directly from the cmd shell.
To run the script directly from cmd shell ie. click "Start" and then select
"Run" and type "cmd". The cmd shell appears. Then type: perl