Check out the 6500-7500 Calibration thread. It has been reported that there are new firmwares available for both units. To find out what firmware you have do the following:
"To check your firmware version, while the projector is on, HOLD the menu button for at LEAST 10 second, release, and then within four seconds, press (sequentially) ESC - ESC - RIGHT ARROW - LEFT ARROW. This is trickier than it sounds, and sometimes take me several attempts to get the service menu to come up. Toward the bottom will be a long number beginning with P - the last three digits indicate your firmware."