I found the problem, and it had nothing to do with ASP or IIS.
It seems that when you register your domain name with Yahoo, and redirect your Domain Name to your IP on their site, you must also go into the "advanced options" and also change your "A Records" to your IP also. They didn't advertise this, or even go out of their way to make it appear important, and so I assumed that the advanced options were optional.
In any case, it turns out that if you don't change your A Records, then your Domain Name is actually pointing to a Yahoo Server, which then redirects trafiic to your IP.
Of course, it also means that you can't access subpages in your site by directly entering the whole URL into your addressbar, nor will Google index your site; HTTPRequests pick up only the response off the Yahoo Server (in my case it also caused me to be unable to access my site from the web from my local PC).
I honestly can't imagine why Yahoo would default in this way. It would mean that by default, sites redirected using their service are broken, when instead Yahoo could default the entries in the A Records to equal the IP Address entered into the original redirection variable. Maybe they like the extra hits?
Anyway, sorry to take up time on your board, I just thought I'd mention the solution in case anybody else makes the same mistake.