> HowEVER.... I tried another of my sites which has an 
index.
> htm, with the rest of it being all php, and it worked! 

if you rename php files into htm, yes. But this should 
never be done (the php code won't be executed)

> Did I miss this in any much earlier thread, or is this 
new to the 
> forum?
php files when seen by the server will always be executed. 
It is considered as security flaw to let the sources be 
displayed to users. php files renamed into htm are specific 
cases, as when you pack php files in a ZIP file.