I have different issues in IE and Firefox, in the same place - viewing a topic. I've linked to screenshots because the site isn't ready for visitors yet.
In the Firefox version, the text of the topic is cut off by a box that appears close around it. In IE the topic text displays but the header part with 'Author' and the menus is too short causing the menu to wrap.
I'm new to WordPress etc. (discovered it five days ago!) but I think I'm doing things correctly. I've tried both bbPress theme packages given in bbPress froum settings (bbPress defauilt and twentyten) and rebuilt the Suffusion bbPress files. That made no difference. If I activate a different theme for the site the above problems go away, but I really like Suffusion.
I'm using WP 3.4.1, bbPress 2.1 (for global forums), BP 1.5.6 (with group forums too, which work) and a few others which I can't see would interfere here.