OK, that is the problem. You need to use the 5.8 installation. I probably need to make that clearer in the documentation now that 5.10 is confirmed not to work. I will have to look into why 5.10 doesn't work but in the meantime please uninstall 5.10 and install 5.8 instead and you should be good to go. EDIT: Actually I was able to get it working with Perl 5.10 as well without any changes to the program. The key is that 5.10 ActivePerl does not come with Tk module installed by default so you have to be careful to install from proper version (the 5.8 Tk module which you can get from CPAN does not work in 5.10). I've updated the documentation at my web site with instructions for ActivePerl 5.10 installation including proper way to install Tk module for it.