update - I found the problem... when I converted my usernames to vbulletin, the usernames in my previous table
had things like "& #39;" for a single quote.
Meaning that it was STORED as "Jim& #39;s Son" in the database when it should have been Jim's Son.
In the post just before this one, the user's name was stored in the database as GS eh& #33; and in reality, it was actaully GS eh!
When I imported into vbulletin, I did not convert the values - once I did a mass update to correct the usernames, all was well.
ticket closed