bbPress.org

@maramac, I would start by trying to validate your XHTML:

http://validator.w3.org/check?verbose=1&uri=http%3A%2F%2Fwww.nyahalcyon.net%2Fforum%2F

There are a few issues there that will not do this to your site (missing alt tags, couple of invalid tags), but it does look like there is a missing div or missed closing div. That might help you.

Also, what sort of tools are you using to help you with this. I find an editor with syntax highlighting (like notepad++ if you’re on Windows) helps a lot, and Firefox with the Web Developer Toolbar also helps a lot to visual things. If you post your platform and your tools, people will be able to post some suggestions. The tools you use can make your job a lot easier.