But when I put mark forums read then eventually close the browser then I come back to the forum it marks threads not read yet. I always thought it was just my work computer but now at home It is starting to happen. I use IE at works and firefox at home.
Are you sure that the threads didn't have a new post in them? I do the same thing as you. I open all the threads I want to read in different tabs and mark the forums as read. Havent had any problems like what your describing.