I think I might have just hit another milestone in trying to debug this problem. I use an index.cgi file in the root of the /www directory to forward subdomains to particular forums.

For example, each subdomain is a mirror of the entire site. However, http://linux.techtalkforums.com forwards you to http://linux.techtalkforums.com/forums/f3.html (which is the linux forum homepage). From there, you can browse the entire site under the linux subdomain.

Now here's the catch. If you traverse the entire site via www.techtalkforums.com all of the google ads displayed are relevant to all of computing (e.g. content is based on techtalkforums.com/forums/index.html). However, if you traverse the entire site via linux.techtalkforums.com, all of the ads are based on linux. If you traverse the entire site via webdev.techtalkforums.com, you'll see only web development links in google regardless of where in the site you are.

It seems as if the google ads are always pulling from the default homepage instead of the current page. Of course, this doesn't happen when directly accessing .php files. Only when accessing their .html counterparts.

This is so frustrating. I can't decide which is more important! Making money by displaying relevant ads. Or hopefully increasing my search engine popularity via static pages!!