Apache is not parsing .php files

Hi, I have a strange problem while trying to run php based applications. Lets start with phpMyAdmin, a very popular open source tool to manage MySQL written in php. I have already installed phpMyAdmin and was running fine. One day suddenly when I pointed my browser at : http://localhost/phpMyAdmin Instead of running the phpMyAdmin browser opened a message window with options- "Open With" or "Save to disk" . I am sure its not browser problem because I tried on Firefox-1.5, Mozilla, Epiphany and Konqueror. One more point I would like to add here that if I write one small php program and save it in as php file (test.php) then http://localhost/test.php executes properly I am using Fedora 2 and apache2, php-4.3x and mysql-3.x were part of the Fedora installation. The only change I made in the /etc/php.ini file was to increase the memory limit from 8MB to 12MB. (Then restarted the http server) Now even php.ini file is in the original state but problem is still there. The http.conf file is unchanged. Can any one give me some sort of idea. Thanks, Sanjay