Sorry, I honestly have no idea how to prevent that. Middle-click does nothing for me, so I can't even test things out. I've done a bit of research at phpbb.com to see if anyone else has the same issue and my searches have come up empty. Normally I just right-click and open in new tab since my middle-click has no effect on opening links. I'm making an inquiry in their support forum. Best I can do for now.