Unable to contact Ispconfig 3 after upgrading Ubuntu to 12.10

[henlem]

After upgrading my Ubuntu server from 12.04 to 12.10 i am not able to get in contact with the admin webpage for Ispconfig 3.

I get the:

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Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator, webmaster@localhost and inform them of the time the error occurred, and anything you might have done that may have caused the error.

More information about this error may be available in the server error log.

Apache/2.2.22 (Ubuntu) Server at server.mydomain.xx Port 80
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I have trawled the log but with no obvious information about the error.

All systems are running and answering the Ispconfig app on my cell phone.
Mails are handled ok - as well as the hosted domains webpages.
Any ideas?