CMS 4.0.2 Installation Error

[محروم.كوم]

Trying to upgrade from 4.0.1 to 4.0.2 and I get this error on step 6 of the upgrade:

Database error in vBulletin 4.0.2:
Invalid SQL:
ALTER TABLE cms_node ADD hidden SMALLINT DEFAULT 0;
MySQL Error : Duplicate column name 'hidden'
Error Number : 1060
Request Date : Tuesday, February 16th 2010 @ 0538 PM
Error Date : Tuesday, February 16th 2010 @ 0538 PM
Script : http://www.boatinghowto.com/install/...ade.php?step=6
Referrer : http://www.boatinghowto.com/install/...ade.php?step=5
IP Address : 76.107.180.11
Username :
Classname : vB_Database
MySQL Version : 5.0.87.d10-ourdelta

What does this mean? How do I fix it?......... What would happen if instead of running the upgrade script I ran Install.php...would it erase anything important or would I lose any data? __DEFINE_LIKE_SHARE__