[GONUMBER6]

I randomly get this database error, not often, just sometimes. Can you tell me what it means?

Database error in vBulletin 4.1.8:

Invalid SQL:

### INSERT QUERY GENERATED BY fetch_query_sql() ###
INSERT INTO dbtech_livewall_settings
(`userid`)
VALUES
('0');

MySQL Error : Duplicate entry '0' for key 'PRIMARY'
Error Number : 1062
Request Date : Tuesday, July 31st 2012 @ 08:11:32 PM
Error Date : Tuesday, July 31st 2012 @ 08:11:33 PM
Script : http://www.englishbulldognews.com/fo...action=options
Referrer :
IP Address : 66.249.71.146
Username : Unregistered
Classname : vB_Database
MySQL Version :