tangent beat me to it but I already wrote it and it covers some CGI stuffage, so here it is.

Probably you have something like this–

use strict;
use CGI ":standard";

# Lots of logic that somewhere results in printing a header...
print header();

# And THEN you try to redirect....
my $url = "http://Myserver/Travel/cgi-bin/A.cgi/";
print "Location: $url\n\n";
exit;
[download]

Which results in–

Content-Type: text/html; charset=ISO-8859-1

Location: http://Myserver/Travel/cgi-bin/A.cgi/
[download]

You only get to print headers once. It’s also possible, but unlikely, your server is configured to send headers for you. As hippo mentioned, the redirect is probably better written this way–

print redirect( -location => $uri );