منتدى استراحات زايد - CMS 4.0.1 CMS/Forum Crashed

I am getting the following message:

Database error in vBulletin 4.0.1. I have tried optimizing and repairing with no success and deactivating all plugins. Can someone help? My forum has been down for 2 days.

Invalid SQL:

SELECT thread.*,post.pagetext AS preview,subscribethread.subscribethreadid,threadre ad.readtime
FROM thread AS thread
LEFT JOIN post AS post ON(post.postid = thread.firstpostid)
LEFT JOIN subscribethread AS subscribethread ON
subscribethread.threadid = thread.threadid AND
subscribethread.userid = 1
LEFT JOIN threadread AS threadread ON
threadread.threadid = thread.threadid AND
threadread.userid = 1
WHERE thread.threadid IN (40622,40532,40594,40623,40618,40602,40619,40616,4 0624,40613,40614,40578,40612,21257,40611,40609,406 17,40621,40555,40620);

MySQL Error : Table './kris_vb2009/post' is marked as crashed and last (automatic?) repair failed
Error Number : 144
Request Date : Friday, May 21st 2010 @ 07:21:11 PM
Error Date : Friday, May 21st 2010 @ 07:21:11 PM
Script : http://www.medicalspouse.com/forums/...e=vBForum_Post
Referrer : http://www.medicalspouse.com/forums/
IP Address : 64.83.217.136
Username : admin
Classname : vB_Database
MySQL Version : 5.1.30