Php Issues

Seems a shame to put so much work into the problem and have it remain unresolved.

Given that nobody else has responded in quite some time, allow me.

As others have stated, ISPConfig seems not to be the issue in your particular case. An Apache or PHP misconfiguration, perhaps, but chances are that the misconfiguration is not ISPConfig's fault. As till stated, untold numbers of users are running relatively unmodified ISPConfig installations without issue (myself included).

Before we proceed any further, have you rebuilt your server since your most recent post?