When I cover the sensor the problem seems to vanish, but the feeling is that the tracking is slightly less stable (other sensors may also be involved when the temperature increases further). It's winter now where I live, so to bring out the problem I have to artificially raise the ambient temperature, but I'm sure that in 2 or 3 months it will become very difficult for me to use this headset. Anyway, in my opinion, covering the sensor can be seen as a temporary solution and a definitive solution should come from the HTC technical staff. It seems very strange that after almost a year there is still no solution to the problem...