Basically the current storage engine, which your table has been setup to use doesnt support FULLTEXT indexes. To solve this you will have delete the table and recreate the table making sure you define the proper storage engine, which would be MyISAM as this engine supports FULLTEXT Indexes.
So what you'll have to do first is delete the cms_articles table, you can do this with phpMyAdmin. Once the table has been deleted. Open up cmstables.php for editing. Now find the following:
Code:
FULLTEXT KEY IdxText (title,body)
)
EOS;
and change it to this:
Code:
FULLTEXT KEY IdxText (title,body)
)
TYPE = myisam;
EOS;
Run cmstables.php again. This should solve the problem.