Classifieds Plug-in throwing up huge error logs & site crashing

Since launching http://www.eqlife.co.uk, we’re getting periodical site crashes triggered by something associated with the WordPress Classifieds plug-in. Error logs output the following query each time resulting in error logs well in excess of 100mb. No other errors (other than a few PHP depreciation messages) are shown.

[13-Apr-2011 10:39:19] WordPress database error Lock wait timeout exceeded; try restarting transaction for query UPDATE 'wp_options' SET 'option_value' = 'a:2:{s:8:"versions";a:2:{s:7:"version";s:5:"2.0.0";s:10:"db_version";s:3:"2.0";}s:4:"data";a:3:{s:17:"post_types_loaded";a:34404:{i:0;b:1;i:1;b:1;i:2;b:1;i:3;b:1;i:4;b:1;i:5;b:1;i:6;b:1;i:7;b:1;i:8;b:1;i:9;b:1;i:10;b:1;i:11;b:1;i:12;b:1;i:13;b:1;i:14;b:1;i:15;b:1;i:16;b:1;i:17;b:1;i:18;b:1;i:19;b:1;i:20;b:1;i:21;b:1;i:22;b:1;i:23;b:1;i:24;b:1;i:25;b:1;i:26;b:1;i:27;b:1;i:28;b:1;i:29;b:1;i:30;b:1;i:31;b:1;i:32;b:1;i:33;b:1;i:34;b:1;i:35;b:1;i:36;b:1;i:37;b:1;i:38;b:1;i:39;b:1;i:40;b:1;i:41;b:1;i:42;b:1;i:43;b:1;i:44;b:1;i:45;b:1;i:46;b:1;i:47;b:1;i:48;b:1;i:49;b:1;i:50;b:1;i:51;b:1;i:52;b:1;i:53;b:1;i:54;b:1;i:55;b:1;i:56;b:1;i:57;b:1;i:58;b:1;i:59;b:1;i:60;b:1;i:61;b:1;i:62;b:1;i:63;b:1;i:64;b:1;i:65;b:1;i:66;b:1;i:67;b:1;i:68;b:1;i:69;b:1;i:70;b:1;i:71;b:1;i:72;b:1;i:73;b:1;i:74;b:1;i:75;b:1;i:76;b:1;i:77;b:1;i:78;b:1;i:79;b:1;i:80;b:1;i:81etc etc......}}}' WHERE 'option_name' = 'classifieds_options' made by require, require_once, require_once, require_once, do_action, call_user_func_array, Classifieds_Core_Data->load_data, update_site_option, update_option

The site is running on the latest versions of WP and BP and all plug-ins are up-to-date. Server details provided below.

Apache/2.2.14 (Unix) mod_ssl/2.2.14 OpenSSL/0.9.8l

PHP/5.3.1

MySQL client version: mysqlnd 5.0.5-dev – 081106 – $Revision: 289630 $

The site is usually bought back up by restarting MySQL services and we’re hoping an increased packet limit will stop the site going down but we could really do with identifying the route of the problem.

I’m completely stuck so any ideas would be a massive help!