I suspect it's a browser issue, not a platform issue .. What browsers are they using on the PC's? on the MAC? Most importantly, are cookies enable on the PC browsers?? is your site blacklisted in their browser? Might be useful to google for "cookie check" and have them try one of those sites, to see if it's all cookie sites or just yours ..

Some code comments:

• Make sure you do use strict; and use warnings;
• The date code (also check out modules like Date::Calc and DateTime) can simply be:

  use POSIX qw/strftime/;
  my $expdate = strftime('%a, %d-%b-%Y %H:%M:%S GMT+', gmtime(time + 108
  +00) );
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• That for can simply be replaced with print @body;
  If you wanted to keep the loop cause you need the index for something, more perlish way is:

  foreach my $i ( 0 .. $#body ){
    print "$i) $body[$i]";
  }
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  Or with loop, but without index:

  foreach my $s ( @body ){
    print $s;
  }
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• no need to keep a $NOS variable -- just use $#body (for last element) or scalar(@body) (for count) when needed
• what do your SetCookieFOO functions look like?