Apache Error 500

Hi, I am using the list comment to decompose urls for navigation. This works fine. Except on one particular server and I don't know why.. if my url is like : test.php everything is ok, but when I use test.php/1, I get the Apache Internal 500 Error. I believe that apache is checking if the 1 in the dir test.php exists, which of course is not the case since test.php is a file. I am only allowed to modify a htaccess file... Does anyone have a suggestion how to fix this? Thanks, Patrick PS: my file test.php looks like list($dummy1,$dummy2,$pid1,$pid2) = split("/",$PHP_SELF); switch( $pid1 ) { case 1: include "file1.html"; break; case 2: include "file2.html"; break; default: include "default.html"; break; }