The code you provided is missing a colon. Is that a transcription error?

D'oh! Now that's really strange -- my actual script only has a single colon, and yet I've run it on Windows using ActivePerl, and it always worked. Weird! Thanks for the sharp eyes! So actually, it's possible that ActivePerl 5.6 just didn't care about the syntax error, while 5.8 did.

What is the exact error message?
Unfortunately I don't have a Windows machine, so I'm just basing this on a user's bug report. He said something nonspecific about "undefined or uninitialized values."

I guess I'd better beg or borrow access to a Windows machine so I can test whether the :: is really the whole issue. Thanks for the sharp eyes, chromatic!