2.1 asks me to download PHP file instead of executing action

I have searched for this but either no one else is having this problem or I just don’t know how to search for this. I am trying to find out if this is a WordPress issue in some way or a server only issue.

Sometimes, when moderating comments or publishing posts, the site will try for a longer time to do what you’ve told it to do but it can’t and a dialog from FireFox will pop up asking me to download moderation.php or post.php. This does not happen every time and when it does, it’s usually only once, canceling the download dialog and trying again usually sends it through after that.

Any ideas? I’m running PHP 4.4.4 and MySQL 4.1.21-standard-log.

Thanks!