Help! Lots of "Can't open file: 'variable.MYI'" errors

Hi,

Got the following errors after installing primary term module, enabling it, allowing it on all my content types and trying to edit a piece of content setting a new primary term. On save the site went haywire and now receive the following errors, if the site loads at all:

* user warning: Can't open file: 'variable.MYI' (errno: 145) query: UPDATE variable SET value = 's:4:\"/tmp\";' WHERE name = 'file_directory_temp' in /usr/local/psa/home/vhosts/visitingarts.org.uk/httpdocs/visitingarts/includes/bootstrap.inc on line 523.
* user warning: Can't open file: 'variable.MYI' (errno: 145) query: UPDATE variable SET value = 'a:6:{s:10:\"refresh:ar\";s:7:\"waiting\";s:15:\"refresh:zh-hant\";s:7:\"waiting\";s:10:\"refresh:el\";s:7:\"waiting\";s:10:\"refresh:hi\";s:7:\"waiting\";s:10:\"refresh:fa\";s:7:\"waiting\";s:10:\"refresh:cy\";s:7:\"waiting\";}' WHERE name = 'javascript_parsed' in /usr/local/psa/home/vhosts/visitingarts.org.uk/httpdocs/visitingarts/includes/bootstrap.inc on line 523.
* user warning: Can't open file: 'variable.MYI' (errno: 145) query: UPDATE variable SET value = 'a:11:{i:0;s:14:\"misc/jquery.js\";i:1;s:14:
\"misc/drupal.js\";i:2;s:56:\"sites/default/modules/extlink-6.x-1.7/extlink/extlink.js\";i:3;s:64:\"sites/default/modules/lightbox2-6.x-1.9/lightbox2/js/lightbox.js\";i:4;s:65:\"sites/default/modules/nice_menus-6.x-1.3/nice_menus/nice_menus.js\";s:10:\"refresh:ar\";s:7:\"waiting\";s:15:\"refresh:zh-hant\";s:7:\"waiting\";s:10:\"refresh:el\";s:7:\"waiting\";s:10:\"refresh:hi\";s:7:\"waiting\";s:10:\"refresh:fa\";s:7:\"waiting\";s:10:\"refresh:cy\";s:7:\"waiting\";}' WHERE name = 'javascript_parsed' in /usr/local/psa/home/vhosts/visitingarts.org.uk/httpdocs/visitingarts/includes/bootstrap.inc on line 523.
* warning: Cannot modify header information - headers already sent by (output started at /usr/local/psa/home/vhosts/visitingarts.org.uk/httpdocs/visitingarts/includes/database.mysql.inc:128) in /usr/local/psa/home/vhosts/visitingarts.org.uk/httpdocs/visitingarts/includes/common.inc on line 148.
* user warning: Can't open file: 'variable.MYI' (errno: 145) query: DELETE FROM variable WHERE name = 'menu_rebuild_needed' in /usr/local/psa/home/vhosts/visitingarts.org.uk/httpdocs/visitingarts/includes/bootstrap.inc on line 544.
* user warning: Can't open file: 'variable.MYI' (errno: 145) query: UPDATE variable SET value = 'a:23:{i:0;i:125;i:1;i:63;i:2;i:62;i:3;i:61;i:4;i:60;i:5;i:59;i:6;i:58;i:7;i:56;i:8;i:31;i:9;i:30;i:10;i:29;i:11;i:24;i:12;i:21;i:13;i:15;i:14;i:14;i:15;i:13;i:16;i:11;i:17;i:7;i:18;i:6;i:19;i:5;i:20;i:3;i:21;i:2;i:22;i:1;}' WHERE name = 'menu_masks' in /usr/local/psa/home/vhosts/visitingarts.org.uk/httpdocs/visitingarts/includes/bootstrap.inc on line 523.
* user warning: Can't open file: 'variable.MYI' (errno: 145) query: UPDATE variable SET value = 'a:0:{}' WHERE name = 'menu_expanded' in /usr/local/psa/home/vhosts/visitingarts.org.uk/httpdocs/visitingarts/includes/bootstrap.inc on line 523.
* user warning: Can't open file: 'variable.MYI' (errno: 145) query: UPDATE variable SET value = 's:64:\"c712d1c17200f92bf59e611acd91c7092d8e0684ce52da95dfc2779285bbb3f6\";' WHERE name = 'drupal_private_key' in /usr/local/psa/home/vhosts/visitingarts.org.uk/httpdocs/visitingarts/includes/bootstrap.inc on line 523.

Help! What does all this mean?