I think the two problems probably stem from the same source, whatever that might be. I've only done some very basic programming, so most of it is over my head too, but I do think we've discovered something that the development folks can use as a starting point.
The phantom page problem is unrelated to search. What happens is that VB stores the thread lengths rather than recalculate them every time they are needed. That means the stored length needs to get updated every time a post is added or removed from a thread. For reasons that aren't entirely clear to me the stored length can get out of sync with the actual length of the thread*. Paging goes off the stored length, so if that is larger than the actual length then there will be a page on the picklist that isn't really there. At least that's the usual cause of things.
Kevin
*There are lots of ways to add, deleted, and or move posts -- probably one of them doesn't correctly update the length.