the problem is that if I do not modify (manually) I can't restart apache; if I can restart apache I can't use ISPConfig admin panel.
I have uninstalled/reinstalled ISPConfig3 (db was lost... no problem...).
Then I tried (if happens to other people) this:
edit each file in /etc/apache2/site-enabled/
removing the SSL section.
Before: copy into another location the files to modify; not in the same folder otherwise apache includes them!!!
Restarting apache2 all is OK.
Now there is another little problem: howto SSL the panel? I connect to:
but this is not a SECURE CONNECTION....
Thank you very much for all.