Inexplicable Access Denied Errors

I'm getting an inexplicable access denied error on the front page page node and a few others.

access denied drupal for full html?
drupal access denied on page don't know why

This assumes that you don't think you have any access control modules operating and don't want access control.

This comment seems to be the way to go:
http://drupal.org/node/128935#comment-212424

One thing it leaves out, delete all node_access rows in your Drupal database except one.

node_access table to the following

nid 0
gid 0
realm all
grant_view 1
grant_update 0
grant_delete 0

For instance, if you leave one row, do this SQL query:
UPDATE dru_node_access SET nid = '0' WHERE nid =1 AND gid =0 AND realm = 'all' AND grant_view =1 AND grant_update =0 AND grant_delete =0 LIMIT 1 ;