500 Error

[elsimultimedia]

Hello.
I am having some problems with ispCP
I have a Ubuntu 8.04 distributions installed on a powerfull server
2 x Xeon 3,06 Ghz
4 GB RAM
...
I installed ispCP Omega 1.0.0 Stable Release
All was fine ( except for a small problem with proftpd users and passwords which i resolved by using the config file provided in the nightly build)
Yesterday i installed some new extensions and updated old ones
* PDO_MySQL
* simplexml
* mcrypt
* hash
* GD
* DOM
* iconv
* SOAP
This morning i noticed tha in ispcp i get a lot of 500 internal server errors

[Tue Mar 31 14:51:37 2009] [warn] (104)Connection reset by peer: mod_fcgid: read data from fastcgi server error.
[Tue Mar 31 14:51:37 2009] [error] [client 192.168.0.2] Premature end of script headers: change_user_interface.php, referer: http://admin.srv1.elsimultimedia.ro/client/index.php
[Tue Mar 31 14:51:39 2009] [notice] mod_fcgid: call /var/www/ispcp/gui/admin/manage_users.php with wrapper /var/www/fcgi/master/php5-fcgi-starter
[Tue Mar 31 14:51:42 2009] [notice] mod_fcgid: process 6848 going graceful shutdown, sending SIGTERM
[Tue Mar 31 14:51:48 2009] [notice] mod_fcgid: process /var/www/ispcp/gui/admin/system_info.php(6848) exit(communication error), terminated by calling exit(), return code: 0

Has anyone encountered this problem?
Any tips?
The server hosts 5 websites with an average of 50 visitors daily so i suppose server load is not a problem.