Invalid SQL? What does this mean?

[OurCouponHome]

Our site says this:

Database error in vBulletin 4.0.6:

Invalid SQL:

INSERT IGNORE INTO session
(sessionhash, userid, host, idhash, lastactivity, location, styleid, languageid, loggedin, inforum, inthread, incalendar, badlocation, useragent, bypass, profileupdate)
VALUES
('a1a6990994d2024125797f7de2e8d8bc', 3, '75.183.62.116', '0ecbc006f9bf61789634356a51e06b26', 1286491736, '/', 0, 0, 1, 0, 0, 0, 0, 'Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Trident/4.0; GTB0.0; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729; InfoPath.2; yie8)', 0, 0);

MySQL Error : The table 'session' is full
Error Number : 1114
Request Date : Thursday, October 7th 2010 @ 03:48:56 PM
Error Date : Thursday, October 7th 2010 @ 03:48:56 PM
Script : http://www.ourcouponhome.com/
Referrer :
Classname : vB_Database
MySQL Version : 5.0.91-log


What does this mean?