Wrap calls to PDO in TRY/CATCH - Sometimes we get a serialisation fault
add to cache clearing from performance page
Add columns to simple_cache to resolve:

PDOException: SQLSTATE[42S22]: Column not found: 1054 Unknown column 'expire' in 'where clause': DELETE FROM {cache_simplecache} WHERE (expire <> :db_condition_placeholder_0) AND (expire < :db_condition_placeholder_1) ; Array ( [:db_condition_placeholder_0] => 0 [:db_condition_placeholder_1] => 1385470183 ) in cache_clear_all() (line 165 of /var/www/html/includes/cache.inc).
Expire not Expires