Uncaught exception thrown... Drush command terminated abnormally due to an unrecoverable error.

I've tried several tweaks and adjustments, but I keep getting this error:

Additional uncaught exception thrown while handling exception.

Original

PDOException: SQLSTATE[HY000]: General error: 2006 MySQL server has gone away: SELECT filename FROM {registry} WHERE name = :name AND type = :type; Array
(
[:name] => ModuleBuilderGeneratorCode7
[:type] => interface
)
in _registry_check_code() (line 3073 of [PATH_TO]/includes/bootstrap.inc).

Additional

PDOException: SQLSTATE[HY000]: General error: 2006 MySQL server has gone away: INSERT INTO {watchdog} (uid, type, message, variables, severity, link, location, referer, hostname, timestamp) VALUES (:db_insert_placeholder_0, :db_insert_placeholder_1, :db_insert_placeholder_2, :db_insert_placeholder_3, :db_insert_placeholder_4, :db_insert_placeholder_5, :db_insert_placeholder_6, :db_insert_placeholder_7, :db_insert_placeholder_8, :db_insert_placeholder_9); Array
(
[:db_insert_placeholder_0] => 0
[:db_insert_placeholder_1] => php
[:db_insert_placeholder_2] => %type: !message in %function (line %line of %file).
[:db_insert_placeholder_3] => a:6:{s:5:"%type";s:12:"PDOException";s:8:"!message";s:218:"SQLSTATE[HY000]: General error: 2006 MySQL server has gone away: SELECT filename FROM {registry} WHERE name = :name AND type = :type; Array
(
[:name] => ModuleBuilderGeneratorCode7
[:type] => interface
)
";s:9:"%function";s:22:"_registry_check_code()";s:5:"%file";s:56:"[PATH_TO]/includes/bootstrap.inc";s:5:"%line";i:3073;s:14:"severity_level";i:3;}
[:db_insert_placeholder_4] => 3
[:db_insert_placeholder_5] =>
[:db_insert_placeholder_6] => http://default/index.php
[:db_insert_placeholder_7] =>
[:db_insert_placeholder_8] => 127.0.0.1
[:db_insert_placeholder_9] => 1352436197
)
in dblog_watchdog() (line 154 of [PATH_TO]/modules/dblog/dblog.module).

---

Drush command terminated abnormally due to an unrecoverable error.

I'm using Drush version 5.4 (could that be the issue?) and the Drupal installation is core 7.16. Any ideas where I should start looking?