IE8 and phpFreeChat (the underlying chat script in jPFChat) have some compatibility issues.

The main problem is a display issue where the userlist (far right side of the chat window) doesn't display where it's supposed to.  Instead, it overwrites the screen on the left side, at the bottom of the chat window.

The WORKAROUND... tell your IE8 users to turn ON the IE7 Compatibility Mode.  They can do this simply by clicking the little broken window icon just to the right of their browser URL navigation box.