Is this due to perl version / build differences?

Correct - our wasn't introduced into perl until 5.6.0. In the mean time you could use vars or just fully declare your variables

use vars qw/%hash/;

%hash = ( ... );

## or

%Your::Package::hash = ( ... );
[download]

See. perldelta on your windows machine to for more information on the addition of our and any other changes between the two versions.
HTH

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broquaint