Try to close the dos-prompt (or cmd.exe or whatever) and reopen it. If that still doesn't work, try to logoff and logon again (or just reboot).

If the first solution fixes the problem, it might help to add the following line to the code above:

$ENV{'The_variable_I_changed'} = 'value';
[download]

This will temporarily add the environmentvariable, but will be gone if you close the shell. But if you reopen another, the system variable from the other code now will be accessible instead.

Sorry, I can't test it because here I don't have access to a Windows-machine in the moment...

Best regards,
perl -e "s>>*F>e=>y)\*martinF)stronat)=>print,print v8.8.8.32.11.32"