Strange behavior of unserialize($_COOKIE[$cookie_name])

Moved to Troubleshooting, since it seems to work perfectly fine for everyone else

What version of PHP do you have?

Interesting
I believe that's the version I have at home and it works fine for me
Could you paste the cookie's value here?

The question is, why are those values being escaped (magic_quotes_gpc is my guess) when we have this piece of code:

// Strip slashes from GET/POST/COOKIE (if magic_quotes_gpc is enabled)
if (get_magic_quotes_gpc())
{
    function stripslashes_array($array)
    {
        return is_array($array) ? array_map('stripslashes_array', $array) : stripslashes($array);
    }

    $_GET = stripslashes_array($_GET);
    $_POST = stripslashes_array($_POST);
    $_COOKIE = stripslashes_array($_COOKIE);
}

Well, PunBB 1.3 uses base64 instead of serialize

1. Sessions aren't necessarily the best things for search engines: they usually end up with the ugly PHPSESSID URLs.
2. We're not really storing lots of information in the cookie: just a user ID and a password hash. If we were trying to store all the user data it would be a better idea to use sessions
3. Session cookies don't save when the browser closes/opens again, so people can't save their logins.

1. Only if you have access to php.ini or a host which allows you to modify PHP's settings via .htaccess. Not always possible.
2. Because we can't trust the data to be up to date or secure (especially in a shared hosting environment)
3. Fair enough

More to it, almost every host using PHP as a cgi or fastcgi can't handle this. That's quite a large crowd.