First, please put your code within code tags when posting. Also instead of retyping your code, it's best to copy/paste to prevent typos (e.g., the missing s on use warning;) and unwanted indentation. Due to the issue I just mentioned, that code won't compile and as such would generate an "Internal Server Error".
After correcting those issues, your code works correctly for me in both IE and Firefox.
Try this adjusted version.
use CGI::Carp qw(fatalsToBrowser);
my $Cgi = CGI->new;
my %cookies = CGI::Cookie->fetch;
my $Cookie = CGI::Cookie->new(
-name => 'test',
-value => 'abc',
-expires => '+2d'
print $Cgi->header(-cookie => $Cookie),