User gets wrong info about new Posts
 

We have an user who claims that he gets always the "new" picture on all forums - even if there is no new posting! I logged in with his username an password and can confirm this behaviour! After loggin in* all forums show a "new" picture in theforum overview. Now I mark one forum as "all posts read" and this forum does not longer show the "new" sign. Now I press F5 to refresh the site and the "new" picture appears again. But when I open this Forum there no unread posts.