Here is the story of what had initially happened:

I went to the local Quick Lube to have the oil changed in my 850 turbo.
While there I saw that they had one of those machines that pumps old
transmission fluid out and new fluid in through the radiator cooling lines, so I asked them to do that. I told them that the lines on the left (driver's) side of the radiator were the transmission cooling lines, but as it turned out they were not, they were the water lines. So when they went to reattach them the brass ferrule that joins the lines to the plastic tank was over-tightened, and was leaking. To remedy this they cleaned the area real good with brake cleaner and then we dripped some super glue onto the area where the brass ferrule joins the plastic tank. We waited for the glue to dry, snugged up the connections a little more, and then started the car and brought it up to operating temperature, and the seal held. I drove it to the hotel, and the seal held from that short 4-mile trip.

Here is the question for the Brickboard:

I suspected that there was still a leak. The coolant level was low
(recovery bottle was empty) and so I got the idea that "just in case"
to put a bottle of the super-duty radiator stop-leak in the recovery tank, and then topped it off with coolant. I brought the car up to operating temperature, and everything appeared fine. Then after one stop, I proceeded on my trip. Six miles later, the transmission went in to "neutral". The selector was in drive but in any gear there was no "go" - the transmission would not engage. I coasted to a safe place to stop and opened the hood, and the recovery bottle was clearly full, and when I opened it the fluid gushed out under a lot of hot pressure. The liquid was gray, meaning the fluid was mixed with the stop-leak. I suspect that the WATER lines that go to the transmission were sealed up by the stop-leak, and that the transmission 'panicked' and went into 'neutral' because it sensed that there was not adequate cooling water circulating through it. The question is, could I flush the cooling system so that there is water circulating through the transmission again, and then the transmission would engage again? The other question is that would just flushing with water clear the passages in through the transmission? If not could I disconnect the radiator connections and clear the lines with a blast of air?