Well, seems something is wrong with your server.php
Do you have some file in /usr/local/ispconfig/server/temp ?
In server.php line 53 there is:
//* Load the server configuration
And I think this should be:
// Load the server configuration
In my server works fine with asterisk but try to remove it.
Line 65 and 100 has tab spaces, you can try removing these lines too.