Yes, both blogs are on the same host.
Both blogs have the same plugins, but none are security-minded.
Before I installed atahualpa on this troublesome blog, I used a theme that came with post thumbnails. I can't see how those posts with thumbnails would affect the comments on pages, but... ???
Maybe I'll try deleting and re-installing all the comments php files......I can't think of anything else to do! Do you think that might work?
Thanks for your help,
Laurie