2.2 Database error

I Just updated my weblog with WordPress from 2.1 to 2.2, but got a code/ message on top of my site:

WordPress database error: [You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ‘GROUP BY year(post_date), month(post_date), dayofmonth(post_date)’ at line 1]
SELECT DISTINCT post_date FROM GROUP BY year(post_date), month(post_date), dayofmonth(post_date)

Does anyone know what has to be put where in my SQL database to solve this problem?
Thanks in advance!