More research reveals:
In firefox, if I can the configuration for network.http.accept-encoding from the the default setting of "gzip,deflate" to "", then I get the pages displayed correctly.
Looking at the headers from the application, it seems that the server is sending gzip'd data with a header that says type="text/html" --
I tried adding in the additional parameters for compression from my 0.92 .htaccess:
php_flag zlib.output_compression On
php_flag register_globals off
At this point, that seems to have no effect on the results.
As the accept-encoding seems to be the default setting for browsers, I really need to solve this before I can put the site up.