I will try the ignition switch suggestion -- although I am surprised that the car can turn if the problem is ignition related.
I have gone through 2 alternators and 2 regulators so far, although the previous comment that they could be burning one another out could be an explaination.
Also, two mechanics have told me that many of the alternators and regulators they are putting out these days are faulty (especially Bosch ones, which is the brand I have). However, I find it difficult to believe that 2 in a row would be duds.