watchdog problem

I wonder if anyone can help me out with this? Having upgraded from mySQL 2.3 to 4.0 I now get a page full of errors when I access my Drupal home page.

Here's the first few lines

# warning: mysql_query() [function.mysql-query]: Unable to save result set in /usr/local/home/httpd/vhtdocs/mooli/blogs/includes/database.mysql.inc on line 153.
# user warning: Incorrect information in file: './aggiesurfclub/watchdog.frm' query: SELECT n.nid, n.vid, n.type, n.status, n.created, n.changed, n.comment, n.promote, n.sticky, r.timestamp AS revision_timestamp, r.title, r.body, r.teaser, r.log, r.format, u.uid, u.name, u.picture, u.data FROM node n INNER JOIN users u ON u.uid = n.uid INNER JOIN node_revisions r ON r.vid = n.vid WHERE n.nid = 7 in /usr/local/home/httpd/vhtdocs/mooli/blogs/includes/database.mysql.inc on line 172.
# warning: mysql_query() [function.mysql-query]: Unable to save result set in /usr/local/home/httpd/vhtdocs/mooli/blogs/includes/database.mysql.inc on line 153.

There's lots more, but it mostly seems to be a problem with watchdog.frm

Any ideas how I might fix this?

Thanks

Ken