Deleted post still shows as Last Post on Index

When a post is made to respond to another post in the forum, the most recent post is usually shown on the forum's Index page and on the topic list on sub forum indexes.

However, we moved a topic to a different sub forum and now the listed topic no longer updates to show the most recent user posting topics on that topical thread's listing in the forum indexes. It remains stuck on the user that posted just before the topic move.

You can see an example of this on our forum at this link:
http://teamlawproductions.com/phpBB/viewforum.php?f=2

The Miscellaneous Topics Index properly shows the topic "The Key", but the "LAST POST" column shows:
"by Cowboy70x7 on 17 Jan 2008 02:15 pm"

Which is not correct.
We even deleted that post but it still shows up in the LAST POST column.