You didn't tell us your flavour of Microsoft OS, but my
guess is it's Win95/98 (later confirmed in the Chatterbox), and if that's the case you simply
can't get the OS to understand "foo.pl" as an executable
file. You could try 4DOS (or whatever they call the Win32 version) as it
should add the capability, otherwise get WinNT or Win2k (or a UN*X variant, but I've got
to work under NT and you can too ;-).