Session logout Problem -- db sessions

[eluser]Stu Green[/eluser]
Is anyone getting this problem?

I'm having log out problems. Sometimes when working lots on a website with lots of page refreshes and posting data, I get logged out sometimes.

My settings are:

$config['sess_expiration'] = 3600;
$config['sess_encrypt_cookie']= TRUE;
$config['sess_use_database'] = TRUE;
$config['sess_match_ip'] = FALSE;
$config['sess_match_useragent'] = TRUE;
$config['sess_time_to_update'] = 1200;