CJ's post describes better than I did what is happening. I can hear the starter solenoid engage and then nothing-no electrical power to any electrical components in any position. The funny thing is that I've had dielectric grease on the battery terminals for years...its the only way I found to keep them from corroding over the span of a month. The battery is less than a year old.

It does help me very much though to know that there isn't an inline switch designed to power down the system as a protective feature. However, according to the Wiring Service Manual there is a "Start Inhibit Switch" located beneath the shifter knob. It looks like the switch has to be closed to complete the circuit and I'm assuming that it is like a "Neutral Safety Switch" on manual transmission vehicles that prevents the vehicle from being started when it is in gear.

One thing I don't understand at all though is why the old key switch, when reinstalled, started the car as usual and the new ones wouldn't. Does anyone else think that is odd or can it be explained logically?
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1993 Volvo 940