I struggled GREATLY with an error recently. IIS 7 failed with a 503 on request and the event log had the following entry.
Log Name: System
Event ID: 5139
I have not fully discerned the problem but a fix was possible.
…Disable IP6 functionality…
There was an entry in the hosts file that looked like “fe80::98er:3968:5b73:2978 ServerName # Added by Office SharePoint Server Search” which needed to be removed.
With IP6 disabled it will not come back. If your farm, like mine, was down you need to disconnect and reconnect all boxes AFTER disabling IP6. This was rather painful as it was late in the AM when an Index server, the culprit with IP6, was attached to the farm.
I hope it is of help to somebody.