If a user ticks "remember me on each visit" when logging in on IE, they get prompted to login again whenever they click on a forum.

I tried adding a cookie prefix, clearing cookies in "my stuff" when logged in, cleared cookies through ie settings, set cookie expiry time to 7 days in config.inc.php file, cleared site cache each time I made a change - all with no luck.

Functions properly in Firefox.
I'm on 7.5.3

Any help would be appreciated, thanks.