whenever i click any one of the threads in the last 10 posts section on the main forum page, it loads the page but then it shows that I have somehow logged out and the page loads as if i am a guest member with all the ads and boxes telling me to register

when i press new reply, it loads the page back on with me logged in and everything is back to normal

it does this mostly with the 10 most recent posts links so i was wondering if anyone could tell me whats up?