Invalid argument supplied

Greetings,

I am using WP Default v1.5 and now all of sudden when I try to open the only category listed I receive the following error message(path name changed for illustrative purposes):

Warning:Invalid argument supplied for foreach() in /home/usr/public_html/blog/wp-includes/functions.php on line 283

Also the following is another WP error message supplied:

WordPress database error: [Got error 12 from storage engine]
SELECT DISTINCT YEAR(post_date) AS year, MONTH(post_date) AS month, count(ID) as posts FROM wp_posts WHERE post_date < ‘2006-09-02 18:22:56’ AND post_status = ‘publish’ GROUP BY YEAR(post_date), MONTH(post_date) ORDER BY post_date DESC

Not exactly sure what happened here because everything was functioning fine and then out of no where this started.

Any help with this would be appreciated.

Regards,
rozmo