Just recently, my right front and my left rear windows stopped working. I thought it might be a fuse or relay since they both stopped at the same time. But checking these didn't reveal any issue there.

When you operate the switch, you hear a faint click from behind the door panel. But they just sit there. Any ideas as to what would cause diametrically opposite windows to stop working?

Do a search for "window" in the 2000+ forum. There'* been a TON of problems with these.

The faint clicks that you hear from behind the door panels would be the Front Passenger Door Module (FPDM) closing in the power & ground to the window motor to " lower", and the Left Rear Door Module (LRDM) closing in the power & ground to "lower". So, hearing the clicks is a good thing in a way, it means that the comms exist between the drivers door module & the other two door modules. And since the drivers window, and right rear window operate, the 30A bkr in the rear fuse block isn't tripped. I'm assuming you're attempting to operate these windows from the drivers door switches. Either mechanical binding, or the drive motors are failing. I know it'* a crazy coincidence for both doors to be inoperable at the same time.

Could both power window regulators have failed at the same time???? I know our cars "eat" regulators, but I have not heard of two of them going out at once.

That is possible. I've tried to find a common link to the symptoms here & come up with nothing. The only thing left imo is to remove interior door panels & water deflectors for closer examination of regulators & window motors/connectors.

To get at the internals look here.
http://www.bonnevilleclub.com/forum/...ndow+regulator

Just for clarity, I've tried all four switches; drivers and passenger'*. It seems my car hasn't been getting enough attention from me and she'* jealous of the Metra train now.

I've lectured my kids about slamming doors on cars. My '76 GP required this, since they were about 100 lbs each. Could this bad habbit be causing something to slip out of whack?

I think the door slamming is what took mine out. The daughter has to slam doors and it was her side that broke