منتدى استراحات زايد

Getting this error when trying to view any page on my site:

Quote:
Database error
The Constant Cognizance database has encountered a problem.
Please try the following:
Load the page again by clicking the Refresh button in your web browser.
Open the www.constantcognizance.com home page, then try to open another page.
Click the Back button to try another link.
The www.constantcognizance.com forum technical staff have been notified of the error, though you may contact them if the problem persists.

We apologise for any inconvenience.
Getting these emails to my webmaster account:

Quote:
Database error in vBulletin 3.8.0:

Invalid SQL:

REPLACE INTO guest
(guestid, hostip, useragent, lastactive, spider, script, rdata)
VALUES
('9dfa0472d544263c54dd20af3aa1476d', '66.249.71.52', 'DoCoMo/2.0 N905i(c100;TB;W24H16) (compatible; Googlebot-Mobile/2.1; +http://www.google.com/bot.html)', 1249281032, 'Google', 'calendar', 'a:11:{s:1:\"c\";s:1:\"1\";s:4:\"week\";s:10:\"127 6387200\";s:2:\"do\";s:11:\"displayweek\";s:5:\"mo nth\";s:1:\"6\";s:10:\"calendarid\";s:1:\"1\";s:1: \"s\";s:0:\"\";s:6:\"postid\";i:0;s:8:\"threadi d\" ;i:0;s:7:\"forumid\";i:0;s:6:\"pollid\";i:0;s:1:\" a\";s:0:\"\";}');

MySQL Error : Incorrect key file for table './constan1_constantvb/guest.MYI'; try to repair it
Error Number : 126
Request Date : Monday, August 3rd 2009 @ 01:30:32 AM
Error Date : Monday, August 3rd 2009 @ 01:30:32 AM
Script : http://constantcognizance.com/forums...ayweek&month=6
Referrer :
IP Address : 66.249.71.52
Username : Unregistered
Classname : vB_Database
MySQL Version :
What's going on? Why did my site die all of a sudden?

I didn't make any changes... worked fine on Friday. Checked it just now today and it's dead. What's up?