it is not only modSnippet that fails, the same error is logged for Users and chunks as well:
[2013-06-25 12:25:02] (ERROR @ /index.php) Error HY000 executing query: SELECT `modUser`.`id` AS `modUser_id`, `modUser`.`username` AS `modUser_username`, `modUser`.`password` AS `modUser_password`, `modUser`.`cachepwd` AS `modUser_cachepwd`, `modUser`.`class_key` AS `modUser_class_key`, `modUser`.`active` AS `modUser_active`, `modUser`.`remote_key` AS `modUser_remote_key`, `modUser`.`remote_data` AS `modUser_remote_data`, `modUser`.`hash_class` AS `modUser_hash_class`, `modUser`.`salt` AS `modUser_salt`, `modUser`.`primary_group` AS `modUser_primary_group`, `modUser`.`session_stale` AS `modUser_session_stale`, `modUser`.`sudo` AS `modUser_sudo`, `Profile`.`id` AS `Profile_id`, `Profile`.`internalKey` AS `Profile_internalKey`, `Profile`.`fullname` AS `Profile_fullname`, `Profile`.`email` AS `Profile_email`, `Profile`.`phone` AS `Profile_phone`, `Profile`.`mobilephone` AS `Profile_mobilephone`, `Profile`.`blocked` AS `Profile_blocked`, `Profile`.`blockeduntil` AS `Profile_blockeduntil`, `Profile`.`blockedafter` AS `Profile_blockedafter`, `Profile`.`logincount` AS `Profile_logincount`, `Profile`.`lastlogin` AS `Profile_lastlogin`, `Profile`.`thislogin` AS `Profile_thislogin`, `Profile`.`failedlogincount` AS `Profile_failedlogincount`, `Profile`.`sessionid` AS `Profile_sessionid`, `Profile`.`dob` AS `Profile_dob`, `Profile`.`gender` AS `Profile_gender`, `Profile`.`address` AS `Profile_address`, `Profile`.`country` AS `Profile_country`, `Profile`.`city` AS `Profile_city`, `Profile`.`state` AS `Profile_state`, `Profile`.`zip` AS `Profile_zip`, `Profile`.`fax` AS `Profile_fax`, `Profile`.`photo` AS `Profile_photo`, `Profile`.`comment` AS `Profile_comment`, `Profile`.`website` AS `Profile_website`, `Profile`.`extended` AS `Profile_extended` FROM `modx_users` AS `modUser` LEFT JOIN `modx_user_attributes` `Profile` ON `modUser`.`id` = `Profile`.`internalKey` WHERE `modUser`.`id` = ? ORDER BY `modUser`.`id` ASC - Array
(
[0] => HY000
[1] => 2006
[2] => MySQL server has gone away
)
[2013-06-25 12:29:46] (ERROR @ /index.php) Error HY000 executing query: SELECT `modChunk`.`id` AS `modChunk_id`, `modChunk`.`source` AS `modChunk_source`, `modChunk`.`property_preprocess` AS `modChunk_property_preprocess`, `modChunk`.`name` AS `modChunk_name`, `modChunk`.`description` AS `modChunk_description`, `modChunk`.`editor_type` AS `modChunk_editor_type`, `modChunk`.`category` AS `modChunk_category`, `modChunk`.`cache_type` AS `modChunk_cache_type`, `modChunk`.`snippet` AS `modChunk_snippet`, `modChunk`.`locked` AS `modChunk_locked`, `modChunk`.`properties` AS `modChunk_properties`, `modChunk`.`static` AS `modChunk_static`, `modChunk`.`static_file` AS `modChunk_static_file`, `Source`.`id` AS `Source_id`, `Source`.`name` AS `Source_name`, `Source`.`description` AS `Source_description`, `Source`.`class_key` AS `Source_class_key`, `Source`.`properties` AS `Source_properties`, `Source`.`is_stream` AS `Source_is_stream` FROM `modx_site_htmlsnippets` AS `modChunk` LEFT JOIN `modx_media_sources` `Source` ON `modChunk`.`source` = `Source`.`id` WHERE `modChunk`.`name` = ? ORDER BY `modChunk`.`id` ASC - Array
(
[0] => HY000
[1] => 2006
[2] => MySQL server has gone away
)