I am running Apache with mod_gzip-1.3.26.1a on Windows XP, and I get problems, such as undefined variables when I run a SQL query. ¶

A tip from Jose Fandos: put a comment on the following two lines in httpd.conf, like this:

# mod_gzip_item_include file \.php$ # mod_gzip_item_include mime "application/x-httpd-php.*" 

as this version of mod_gzip on Apache (Windows) has problems handling PHP scripts. Of course you have to restart Apache.