I looked at that thread and did your proposed steps:
dingle@its:/etc/httpd/conf/vhosts# /usr/sbin/httpd -t
Syntax error on line 187 of /etc/httpd/conf/vhosts/Vhosts_ispconfig.conf:
Invalid command '...', perhaps misspelled or defined by a module not included in the server configuration
However, the latest VHOST file doesn't have that anymore. It has the full egroupware directive. BUT, I deleted egroupware from the ISPCONFIG Apache Directives two weeks ago. It never updated to the Vhost configuration file.
Basically, ISPCONFIG is not doing three notable things:
1) It is not updating the Vhost config file.
2) It is not changing user's passwords.
3) It is not changing mail settings.
Nothing was altered setting-wise on the machine. It just stopped letting us modify stuff sometime this past month.