So this turned out to have nothing to do with jQuery really. In the course of solving the problem for our web site, I switched from using pngfix_map.js (which only deals with images in the DOM and requires CSS-applied PNG background images to be dealt with separately in IE6-specific CSS files) to using iepngfix.js (which deals with both DOM images and background images via jQuery calls). Incidentally, I edited iepngfix.js so as to allow me to specify the sizingMethod for the AlphaImageLoader filter. This was necessary so that I could "fix" the repeating background image of the panel on which the a-links had died.
I found the information on this page http://www.satzansatz.de/cssd/tmp/alphatransparency.html to be very useful. One of the links on that page led me to this page http://www.daltonlp.com/view/217 where the "Addendum: IE link bug" section provided the clue that the dying of a-links can be related to the DIMENSIONS of the PNG image in question. Unbelievable!! But that turned out to be the key in my case. By reducing the repeating background image to 1 pixel high, all the a- links came alive again. It's a miracle! Sorry for wasting your time on this forum. Oh to be able to fast-forward to a time when IE6 is a distant memory!
