Sorry, but it's on your end.
Did you force-configure your browsers to forget cookies at the end of your session? Firewall? Something?
(MSIE6? Seriously?
http://www.theie6countdown.com/default.aspx )
Code:
POST /forums/login.php?do=login HTTP/1.1
Accept: <snip>, */*
Referer: http://thefiringline.com/forums/newreply.php?do=newreply&noquote=1&p=4599310
Accept-Language: en-us
Content-Type: application/x-www-form-urlencoded
User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; ...)
Host: thefiringline.com
Content-Length: 204
Connection: Keep-Alive
Cache-Control: no-cache
Cookie: __utma=X; __utmb=X; __utmz=X; bbsessionhash=X; bblastvisit=X; bblastactivity=0; __utmc=X
vb_login_username=Miata+Mike&cookieuser=1&vb_login_password=&s=&securitytoken=guest&do=login&vb_login_md5password=X&vb_login_md5password_utf=X
HTTP/1.1 200 OK
Set-Cookie: bblastactivity=0; expires=Sun, 27-May-2012 15:37:42 GMT; path=/; domain=.thefiringline.com
Set-Cookie: bbuserid=102508; expires=Sun, 27-May-2012 15:37:42 GMT; path=/; domain=.thefiringline.com; HttpOnly
Set-Cookie: bbpassword=X; expires=Sun, 27-May-2012 15:37:42 GMT; path=/; domain=.thefiringline.com; HttpOnly
Set-Cookie: bbsessionhash=X; path=/; domain=.thefiringline.com; HttpOnly