Sorry, I should've mentioned I don't know what might help you, and was just giving some general advice.

FWIW, I've heard of some versions of IE caching pages including headers, leading to strange behaviour with cookies. To see if you suffer from caching woes, you can try the following snippet which I've filed away under overthetop_anticache.pl:

use POSIX qw(strftime);

print header(
    # date in the past
    -expires       => 'Sat, 26 Jul 1997 05:00:00 GMT',
    # always modified
    -Last_Modified => strftime('%a, %d %b %Y %H:%M:%S GMT', gmtime),
    # HTTP/1.0
    -Pragma        => 'no-cache',
    # HTTP/1.1
    -Cache_Control => join(', ', qw(
        no-store
        no-cache
        must-revalidate
        post-check=0
        pre-check=0
    )),
);
[download]

Makeshifts last the longest.

-expires => 'Mon, 26 Jul 1997 05:00:00 GMT',

Dare I point out that 26 July 1997 was actually a Saturday?
And, yes, I hate the fact I checked too. ;-)

davis
Is this going out live?
No, Homer, very few cartoons are broadcast live - it's a terrible strain on the animator's wrist

LOL, ++ just for the pedantery. :) (Upd.: Thanks for that hint, too. ;) )

Makeshifts last the longest.