Forum Can't find user's posts before upgrade date
 

On may 2012 i've upgraded forum version from 3.7 to 4.12. All upgrade operations were done properly without critical errors.

But now when anyone clicks on "user's posts" in his profile or uses advanced search - all posts by exact user he can find are only after date of upgrade.
So you can't find user's posts before the date of upgrade (threads and posts are all present and available)
maybe i need to rebuild some indexes or smth ?