A significant percentage of our members use the Firefox browser (as I write this I checked and of the 13 users currently viewing the forum, 6 were using firefox), so I don't believe that's the problem in and by itself.

FWIW, Firefox is my browser of choice and I haven't personally experienced the problems you describe. I view the forum with my monitor set for 1024x768 resolution using the default (normal) text size and no side panels open.

Are you viewing the forum using this link:
or this link:
Do both give you the same problem?