Problem Reading session files

I am about to pull my hair out trying to figure out why this isn't working. I figured I would wait and hope that someone else's eyes would pick something up, though. I am running it on 4.04pl1 CGI / Win 2k / IIS 5. I am trying to read from the session files that are in C:\php\sessiondata in order to create an administration script to open up each session file, grab each username variable that I have registered in it, and print the names to the screen. This is the code I have with comments describing what is happening when I run it: function show_loggedin_users() { $loopcounter=0; if ($dir = opendir('c:/php/sessiondata')) { while($files = readdir($dir)) { if (substr($files,0,1) != '.') { //don't want the '.' or '..' files $sess_id[$loopcounter]=substr($files, 5); //get the sid from the filename (removes the sess_ from the filename) $fullfilepath='c:/php/sessiondata/'.$files; $fp = fopen($fullfilepath, "r"); //open up the session's file $fcontents = fread($fp, filesize($fullfilepath)); //get the contents of the file - it won't, though! echo $fcontents; //just to check to see if it worked - it doesn't print anything fclose($fp); ... There is a session file in the directory, there are registered variables in the file, and I can print $fullfilepath and get a correct path and filename to the file. I also tried fgets instead of fread. Nothing seems to work, though... Any corrections/thoughts/comments are appreciated.