I went home for lunch and tried logging in from there, and did not have the problem.   When I got back to work I tried logging in from the computer where I was having the problem before, and this time all was well.  So, I changed the configuration back the way it was before the problem occurred, and it was still working correctly, including Windows LiveID log in. 

Except I didn't try putting the Windows LiveID site in an IFrame again, since that seemed to trigger the problem, and I don't really know what fixed it.  I would like to be able to put the Windows LiveID site inside an IFrame (so users can view their email inside the frame).  Does anyone know why that might break the log in process?  Maybe it didn't break it and it was just a coincidence, but I am afraid to try it again without more info.

Thanks for any light you can shed on this.