I have been doing some digging and I think I have found the issue, but not teh solution. The issue is with VB 4.2.2. It requires a PHP version of 5.2 or higher. I'm running 5.3. Well, this version tosses more error codes than the last php version. I think the forum is waiting for an error, but because I have globally blocked them, it's not getting them. And then it times out, and asks you if you want to leave the page. However, your post has actually posted in the background, you just can't see it.
I'm still working on this. Need to do some more hacking...