Thanks for looking guys. There are messages in /var/log/httpd/admin_error_log as follows. I did the iptraf.i386 update via the User Manager in the normal way without changing repositories. I noticed the problem when doing the update, but it may have been there earlier.
[Sun Dec 12 18:35:50 2010] [error] [client 127.0.0.1] fileparse(): need a valid pathname at /usr/lib/perl5/vendor_perl/5.8.5/CGI/Persistent.pm line 30, referer:
https://dellmail/user-manager/cgi-bin/userpanel-navigation[Sun Dec 12 18:35:50 2010] [error] [client 127.0.0.1] Premature end of script headers: reboot, referer:
https://dellmail/user-manager/cgi-bin/userpanel-navigation[Sun Dec 12 18:41:47 2010] [error] [client 127.0.0.1] fileparse(): need a valid pathname at /usr/lib/perl5/5.8.5/File/Basename.pm line 175, referer:
https://dellmail/user-manager/cgi-bin/userpanel-navigation[Sun Dec 12 18:41:47 2010] [error] [client 127.0.0.1] \tFile::Basename::fileparse('undef') called at /usr/lib/perl5/vendor_perl/5.8.5/CGI/Persistent.pm line 30, referer:
https://dellmail/user-manager/cgi-bin/userpanel-navigation[Sun Dec 12 18:41:47 2010] [error] [client 127.0.0.1] \tCGI::Persistent::new('CGI::Persistent', '/var/cache/e-smith/formmagick/sessions') called at /usr/lib/perl5/site_perl/CGI/FormMagick.pm line 198, referer:
https://dellmail/user-manager/cgi-bin/userpanel-navigation[Sun Dec 12 18:41:47 2010] [error] [client 127.0.0.1] \tCGI::FormMagick::new('esmith::FormMagick', 'type', 'string', 'source', '<form title="FORM_TITLE" header="/etc/e-smith/web/common/head...', 'charset', 'UTF-8', 'sessiondir', '/var/cache/e-smith/formmagick/sessions', ...) called at /usr/lib/perl5/site_perl/esmith/FormMagick.pm line 222, referer:
https://dellmail/user-manager/cgi-bin/userpanel-navigation[Sun Dec 12 18:41:47 2010] [error] [client 127.0.0.1] \tesmith::FormMagick::new('esmith::FormMagick') called at /usr/lib/perl5/site_perl/esmith/FormMagick/Panel/useraccounts.pm line 117, referer:
https://dellmail/user-manager/cgi-bin/userpanel-navigation[Sun Dec 12 18:41:47 2010] [error] [client 127.0.0.1] \tesmith::FormMagick::Panel::useraccounts::new('esmith::FormMagick::Panel::useraccounts') called at /etc/e-smith/web/panels/user/cgi-bin/useraccounts line 34, referer:
https://dellmail/user-manager/cgi-bin/userpanel-navigation[Sun Dec 12 18:41:47 2010] [error] [client 127.0.0.1] Premature end of script headers: useraccounts, referer:
https://dellmail/user-manager/cgi-bin/userpanel-navigation