Database error once in a while - unsure if its config or an attack
 

I get this perhaps once a day only since very recently:

Code:
Database error in vBulletin 3.8.2:
Invalid SQL:
SELECT userid, username FROM user
WHERE userid != 0
AND (
username = 'знакомства'
OR
username = 'знакомства'
);
MySQL Error : Illegal mix of collations (latin1_swedish_ci,IMPLICIT) and (utf8_general_ci,COERCIBLE) for operation '='
Error Number : 1267 Request Date : Friday, April 24th 2009 @ 05:08:51 PM
Error Date : Friday, April 24th 2009 @ 05:08:51 PM
Script : http://www.archeli.com.au/forums/reg...p?do=addmember
Referrer : http://www.archeli.com.au/forums/register.php
IP Address : 95.220.47.205
Username : знакомства
Classname : vB_Database
MySQL Version :
Is this a configuration issue with my database or someone trying to access/register on the site with an intentionally obscure/problematic username?>

Advice appreciated team!
Will