MYSQL Error suddenly

MYSQL ERROR
Error: Duplicate entry '0' for key 'Account_ID'
Query: INSERT INTO `fl44_listings_shows` ( `Listing_ID`, `IP`, `Date`, `Account_ID` ) VALUES ( '2283', '81.224.118.83', NOW(), '0' )
Function: countVisit
Class: rlListings
File: /home/fyndklip/public_html/includes/controllers/listing_details.inc.php (line# 65)

This goes for all listings and I haven't done anything til' this suddenly appeared.

Have filed a ticket.

//Morgan

OK I think I fixed it with repair and flush but wonder why this suddenly happened?

//Morgan