[Mediawiki-l] Install/config - wants me to d/l the php files instead of execute them

[Belorion]

I've gone through and installed MediaWiki 1.5.2.  I did not enounter any
problems during the install process -- it seemed to all go smoothly.
However, when I click on "create an account" instead of sending me to a page
it asks me if I want to download the PHP file (index.php).  If I click on
"edit" on the main page, I get the edit box, but when I hit save I get the
same "do you want to download this php" prompt (index.php).

I have PHP working on many things on this server, including phpBB2 and
WordPress.  What am I missing here that the server wants me to download the
.php files instead of processing them?  Any suggestions?  Thanks.

Matt