Anyone know how i fix this error

[Mancunian_Red]

Database error in vBulletin 3.7.3:

Invalid SQL:

SELECT COUNT(*) AS count
FROM post AS post
LEFT JOIN threadread AS threadread ON (threadread.threadid = post.threadid AND threadread.userid = 1)
WHERE dateline >= 1235857518 AND dateline > IF(threadread.readtime IS NULL, 1235010424, threadread.readtime)
AND visible = 1;

MySQL Error : Table './mancred_techwars/post' is marked as crashed and should be repaired
Error Number : 145
Request Date : Saturday, February 28th 2009 @ 08:27:04 PM
Error Date : Saturday, February 28th 2009 @ 08:27:04 PM
Script : http://www.techwars.co.uk/index.php
Referrer : http://www.techwars.co.uk/admincp/index.php?do=head
IP Address : 217.171.129.72
Username : Mancunian_Red
Classname : vB_Database
MySQL Version : 5.1.30

Any help would be appreciated i am stuck i honestly don't know what i have done wrong.