Then back to your first post.
Will upgrading resolve the issue.
POSSIBLY.
There were some tweaks made to the search function after 7.5.
As far as gizmo and myself we are using the current version and it works. In fact you can search here for "the" and get results.
Using the UBB internal option bypasses any MYsql limits imposed such as number of characters or keywords. (and,or,etc)