cannot load php page, please help

[feelexit]

I have nginx, php 5 and php5-fpm installed on ubuntu 10.04 server
edition.

After I started the nginx server, I have no problem loading the regular
html pages. but all .php pages cannot be viewed, firefox just pop out a
window asking me if I wnat to download the file.

I also tried IE, on IE, it just shows the source code.

I checked both nginx and php5-fpm error log files, didn't see any
errors. did I miss something during the configuration?

I dont know if the problem is nginx or php5_fpm,  I need someone to
point me to the rite direction

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,134116,134116#msg-134116