Yeah I remember, I did install it for her and integrated her site and forum a while ago. It clearly was working before, as I did a quick search in her site and forum databases in phpmyadmin. As you can see from the two screenshots, the users tables in site and forum databases start to diverge after user ID 25(until ID 24 everything was in sync), where the site has user 'test5' and the forum has user 'test7'. Everything has been out of sync after user ID 25:
Site User Table Forum User Table
So what I conclude so far is that something happened at the time when she created the test user 5 and it was only inserted to adoptables site database but not forum database. It can be several reasons, and these are the questions that need to be answered:
1. Did she modify the script in some way that broke forum integration, at about the time account test 5 was created?
2. Was the site down/offline right after she created the account test5, so the forum user aint created properly?
3. Did anyone try to register on the forum, and not on the site? Its necessary to turn off forum registration.