Install on XP worked, then didn't

["Richard C. Steffens" <rsteff@xxxxxxxxxxx>]

Yesterday I installed Apache 2.2.4 and php_5.2.2 on my laptop that runs
Windows xp Home Edition. I used the msi installer for each and I edited
httpd.conf to use:

DirectoryIndex index.php

When I finished, I was able to see the usual long list from an index.php
file in the htdocs directory containing only:

<? phpinfo(); ?>

Since then I have rebooted the machine, and while Apache still works,
php no longer does. I ran the msi installer again and used the repair
feature, but nothing changed. I also confirmed that Apache works by
changing DirectoryIndex back to index.html. I assume it doesn't matter
that I changed DocumentRoot to:

"D:/LocalWebServer/htdocs"

Where do I start looking to solve this problem?

Thanks.

-- 
Regards,

Dick Steffens