Showgun 2.5 lamp dousing

Hi, we have 16 Showbeams and 16 Showguns 2.5 in our show and I have 3 Showguns 2.5 that from time to time douse their bulb when the unit comes back from standby mode and opens the dimmers. The message on the display says the fans cut the lamp but all the temp readings and fan speeds are similar with a unit that doesn't douse. All the units are running firmware 1.1.11 and they are brand new. Please advice
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