acrylian, thanks for your suggestion. I'll talk with the assistence of my hosting company after the new year holidays.
Merry Christmas and Happy New Year to you and to everybody around here!

I believe ways to specify what types of items are subject to these rules, but I have not studied them. Perhaps that can be added to the plugin, but probably not until after the 1.4.0 release.

Update:
There were still some cache problems with IE8, even with the no cache header reported above, so I decided to disable mod_expires via .htaccess with the following lines:

ExpiresActive Off

Now everything seems to work better, included a proper behavior of browser's navigation buttons