Are you using the tab browsing? If so you can open Firefox twice and with the tab browsing it'll open another tab in the same window. Leaving the
other alone. I think.
I have a problem with ATS/firefox aswell, but only on my laptop.
When I click on a link to open a topic on the board, it opens in the same window, which is normal. But the browsers back button doesnt take me back to
the previous page, but reloads the currents page instead. Quite annoying..
This problems only appears on ATS, all other sites work perfectly normal.
That usually happens when the previous page redirects to the one you are seeing, so going back one page sends you back from where you came.
If that is the case, the history button near the back and forward buttons should show you that there was a page in between the one you came from and
the one you are in now.