Any ideas about this?? thanks....

What code are you running? Which versions of DateTime and DateTime::TimeZone do you have? (these are crucial details)

I encounter no such behaviour, see

use DateTime;
use Cwd 'cwd';
use strict;
use warnings;

print 'DateTime->VERSION ', DateTime->VERSION,$/;
print 'DateTime::TimeZone->VERSION ', DateTime::TimeZone->VERSION,$/;
print cwd,$/;

eval { DateTime->now( time_zone => 'local' ); 1} or print $@,$/;
DateTime->now( time_zone => 'America/Los_Angeles' );

print cwd,$/;

__END__

DateTime->VERSION 0.1901
DateTime::TimeZone->VERSION 0.2503
C:/dev/LOOSE
Cannot determine local time zone

C:/dev/LOOSE
[download]

I'm using ActivePerl flavored perl on win32.