I'm not sure exactly why the code barfs (i don't have a windows machine to play with), but you may want to check out
LWP::Parallel, which does web requests in parallel without making you deal with
forking.
BlueLines
Disclaimer:
This post may contain inaccurate information, be habit forming, cause atomic warfare between peaceful countries, speed up male pattern baldness, interfere with your cable reception, exile you from certain third world countries, ruin your marriage, and generally spoil your day. No batteries included, no strings attached, your mileage may vary.