MySQL Error

[DaChief]

Everytime a user tries to registrate on my site, I get a MySQL DB Error:

Invalid SQL:
INSERT INTO userfield
	(userid)
VALUES
	(114);

MySQL-Fehler  : Doppelter Eintrag '114' f?r Schl?ssel 'PRIMARY'
Fehler-Nr.    : 1062
Fehler-Zeit   : Friday, 11.05.2012 @ 12:09:51
Datum         : Friday, 11.05.2012 @ 12:09:51
Skript        : http://www.multirotor-community.eu/forumrunner/request.php
Referrer      : 
IP-Adresse    : 212.17.66.3
Benutzername  : test
Klassenname   : vB_Database
MySQL-Version :

This is really annoying, because users can't sign up on my site!
Can anyone help me please?
I already tried to repair/optimize tables and reset Cache.

I also went to the db via phpAdmin but can't really find the issue

[kh99]

I believe it's saying that the userfield table already has a value of 114 for the primary key (userid), and you're trying to insert another userid of 114. In other words it's trying to create a user with a duplicate userid.

It's hard to say what to do without knowing exactly what's going on, but I suppose what you want to do is figure out what the highest userid in the user table and see how that compares to the userfield table.