It actually appears that I had the wrong password.
I executed the following:
Code:
SELECT password FROM user WHERE userid=MyID;
I got the password hash, then used this to change it:
Code:
UPDATE user SET password=MD5(concat(MD5('MyPassword'),user.salt)) WHERE userid=MyID;
I then checked the password hash again, and it was different.
I don't remember changing it, but everything else seems okay. I'm still waiting on response from my users to make sure they can all log in okay.