It has been limping along for a little while now and I have been dealing with the issues as best I can. It took me the better part of a day for Apple and I to agree on the conclusion of a bad logic board, but in the end it will have been troubleshooting well worth the time and effort.

Tomorrow, someone is supposed to be here to replace the board and with any luck, both I and my trusty iMac will be happy again.