Probably a phpBB3 issue.

For every forum site I visit: I normally click New Posts to get a list of posts I might be interested in. Then I go down the list and Control-Click the "newest post" link for each thread I want to read. This opens that thread in a new Firefox tab in the background. When I've done this for all interesting threads, the first few threads should have finished loading in their tabs. I then go left to right through my tabs, reading each thread, while later threads continue to load. I never need to wait for a thread page to load, no matter how many images it has.

Alas, it looks like phpBB3 is intercepting Control-Click. So when I do that to the "newest post" link, the thread opens both in a new tab and in the current tab. So I have to keep clicking the Back button to get back the list of new threads.

There is a onclick event for the rows that opens the link using javascript.
This could be the problem.

I use middle click on the text of the link (click down of the scroll wheel) to open new tabs, so I havn't ran into this issue.

Apparently the default MS HID driver in Vista 64 doesn't recognize the middle (wheel) button of my Logitech Revolution. I guess I'll have to investigate to see what can be done about that.

I had the same issue with vista nd my logitec mouse. I had to change the button to a generic button to make the middle click open new tabs as I use the middle click to open/close tabs on every other machine I use.

Installing the latest Setpoint enabled the middle click. I'd had bad experiences with Setpoint in the past and had avoided installing it.