> ww: For all practical purposes, windoze ignores that shebang, but ultimately, execution will be on a Linux box (Apache).

IIRC there are various methods on Win to associate script-files to a executable (and none is default) ...

> ww: 5.24, ActiveState, on dev box, Win7 pro

... so probably you should check if you have multiple Perl installations on your machine.

Try to run the code directly with the same perl.exe which was used for the syntax check and see if the errors still differ.

update

Probably you want to prepend this to your script

BEGIN { warn "Exe:$^X , Ver:$^V , File:$0" }
[download]

and compare the outcome in your different runs.

See perlvar for details