Database Error - Calendar?

[smooth-c]

I've been getting this database error for about a week or so now. I can't work out any change that I've made that could have caused this, so I hope someone can help.

Database error in vBulletin 4.1.2:

Invalid SQL:

               SELECT calendarpermission.usergroupid, calendarpermission.calendarpermissions,
                       calendar.calendarid,calendar.title, displayorder
               FROM vb_calendar AS calendar
               LEFT JOIN vb_calendarpermission AS calendarpermission ON
                       (calendarpermission.calendarid = calendar.calendarid AND
                               usergroupid IN (1))
               ORDER BY displayorder ASC;

MySQL Error   : Unknown column 'calendar.calendarid' in 'field list'
Error Number  : 1054
Request Date  : Tuesday, April 12th 2011 @ 05:26:29 AM
Error Date    : Tuesday, April 12th 2011 @ 05:26:29 AM
Script        : http://www.xx.com/discussion/calendar.php?c=1&do=displayweek&month=1&week=1261872000
Referrer      :
IP Address    : 38.101.148.xxx
Username      : Unregistered
Classname     : vB_Database

The calendar seems to work fine when I use it. Strange. I've been getting on average.. 20 emails a day with this error?

Thanks