I’ve been running into problems ever since I upgraded WordPress to 2.x (not sure if it was 2.0 or 2.1) with new posts. The first time a new post was was loaded into the browser, the server kicked out this error:
PHP Warning: mysql_affected_rows() [<a href='function.mysql-affected-rows'>function.mysql-affected-rows</a>]: A link to the server could not be established [...]