There is evidence on the AVS forum that Mitsubishi has issued a firmware update, version 4 to overcome the dust problems on the LCD panels. Projektortuning.de refer to a Mitsubishi Press release issued on 17-04-2007 describing the firmware update as a "Dust Protection System". It would seem that the exhaust fan is intelligently programmed to increase for a few seconds at a time to eliminate dust particles. Mitsubishi UK are not aware of this and have offered to investigate and ring me back. It will be one week tomorrow and I haven't heard anything yet.