Error: Unable to open *\index.php in Unknown on line 0

Hi ya all! I'm having some trouble with PHP on IIS. Yes, I know IIS suck! When I have one website, I have no problem. But when I have more than one website on IIS. This is when I have problem with PHP. I looked up on php.ini to make sure the line, "doc root = " is left blank and the other line, "include_path = " is left blank also. It seem that php.ini can't work with multiple website on IIS that each website have different directory and seperate directory. So, what's hte problem and what do I need to do to fix it? Thanks, Scott