I don't think those messages you're seeing are related to your problem. I have plenty of those same log entries and mine is working fine.

My first question would be permissions. I see your listing of permissions for the directory, but not the permissions on /opt/xymon/data, /opt/xymon, and /opt... what are those. If eXecute permissions aren't set on all parent directories, I don't think other users can read from there.

Also.. is SELinux getting in your way? SELinux used to bite me a lot when I first stopped disabling it and actually working with it.

Check SELinux Status: #> getenforce

If it returns "Enforcing".. you'll have some additional work to do:

Set SELinux to "Permissive" mode.. but do NOT leave it like this: #> setenforce 0

There are better tools for this in RHEL/Centos 7, but this is what I do to get by in previous versions..

Make note of NUM_OF_LINES in the log file #> LINES=$(wc -l /var/log/audit/audit.log | awk '{ print $1 }')

Next, run the Xymon GUI through it's paces.. Look at graphs, enable/disable monitoring, acknowledge alerts, edit critical systems, everything you can think of..

Then, generate a custom SELinux policy module using the log entries you generated by running Xymon in permissive mode: #> sed -n "$(($LINES + 1)),$ p" /var/log/audit/audit.log | audit2allow -M xymon

Install the new policy module: #> semodule -i xymon.pp

Restore SELinux to "Enforcing" mode: #> setenforce 1