This is a common problem that crops up when people are replying to posts. You write your message, hit "Preview," look it over, then hit "Submit" and... instead of it magically appearing on the forum, you get this message: Invalid Session. Please Resubmit the Form.
I could explain why I think this is happening, but that'd get kind of technical and I'd be way over my head within minutes. Let me just say that:
* I think it's related to AOL (which secretly switches your internet address at regular intervals while you're doing things on the internet, confusing every other website that likes to keep track of who is doing what where), and
* I think the best thing to do is just go back and hit "Submit" again until it works. At this point. I may be able to fiddle with some code in the posting body template (the file that tells the board what to do when someone hits "Reply"), but that'll take time and effort, and someone more familiar with php than I am right now.
If this doesn't work, lemme know about it. Email is linked under that "profile" button at the bottom of this post, or at the bottom of most pages of the main website.