PHP 5 and IIS 6 Problem

Hello everyone,

I'm quite new to PHP so please excuse with my lack of knowledge.

I am running PHP 5.2.6 on Windows 2003 Server with IIS 6.0 ISAPI.

After installing, I am having two, probably related, problems.

1. It appears that PHP is working, however, it only works for some of the
domains. For instance, I have mydomain.com and PHP is working but it doesn't
work on the identically configured test.mydomain.com with identical pages.
The test.mydomain.com throws a generic 404 error.
2. Some PHP sites that I host (I don't develop in PHP) will have pages that
will not render at all. For instance, I have a photo gallery that the
index.php renders correctly but when you navigate to any other page, you get
a completely black page back, including the source being blank.

I might just be overlooking something obvious but I've been wrestling with
this for a few days now and can't seem to figure it out. 

Any help is greatly appreciated!

Ryan