[MagicalTux]

It's due to the way vBulletin works... It seems that the "search index" was not converted during the upgrade. It is updated everytime someone posts on the forum.

There is probably a way to rebuild it, but it will take a long time considering the number of posts on the forum...

Also, the limitation of number of letters in the search is due to the same thing.. The search index would be too big if every words was indexed...