Does this happen to anyone else? Computer related
 

I am a member of another message, for reef aquariums. It is very similar to this board in regards to the sponser adds in small link boxes. This board they are on the left side, the other board they are on top. Every once in a while when I am on the other board, and I use the "back" button to the previous page, there is an add from this board on the page. When I click on it, it links to the aquarium sponser. So far I have seen Dollar Offshore, Drambue on Ice, and one other.

Is this unusual? Do I have some kind of virus?

Thanks

Wow sounds a little different there, I know if you sign up to EZ board? you can use many different boards with the same user name I don't know about your situation though