Remove Session based caching

Hi:

Recently we found in our site that the sessions table frecuently broke and starts to get hard disk space beyond the stars. Also, randomly our website broke and star to show messages like that:

Warning: Got error 127 from storage engine query: SELECT u.*, s.* FROM users u INNER JOIN sessions s ON u.uid = s.uid WHERE s.sid = '4b5350a9fad979cbfba61a25ddc6d6fa' in /usr/www/users/xxxx/xxxxx/includes/database.mysql.inc on line 172

and then

Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /usr/www/users/xxxxxx/xxxxx/includes/database.mysql.inc:172) in /usr/www/users/xxxxxx/xxxxx/includes/bootstrap.inc on line 811

A drop of the sessions table returns back to normal.

We discover that custom pagers inflate the sessions table includin the node numbers of (seems) all post ... and we have almost 40.000 post on our website.

The error that Drupal give us on Watchdog looks like:

The table 'sessions' is full query: INSERT INTO sessions (sid, uid, cache, hostname, session, timestamp) VALUES ('b151c9946087200dd958c415e8becb6c', 0, 0, '66.249.65.178', 'custom_pagers|a:1:{i:1;a:2:{s:4:\"data\";s:168185:\"31625,31624,31623,....... here was a looooooooooooooooooooooooong list of nodes ...............13662,14088,14173,20513\";s:9:\"timestamp\";i:1217460708;}}', 1217460709) en la línea 172 del archivo /usr/www/users/xxxxxxxx/xxxxx/includes/database.mysql.inc.

The problem is that the table sessions gets 2 GB, and then, broke. We move Sessions from MyISAM to InnoDB to avoid the problem of the file size limit of the table, but: there is a way that to avoid that custom pagers add all this number nodes to the sessions table?

Thank you in advance.