I observe this happening when lamps using CFL bulbs are first tuned on. It seems before the lamp 'warms up' and gets its full luminance, it radiates a lot of IR radiation, which swamps the IR receiver in the Hummy. Other items may not be affected as they may use a different frequency of pulses to modulate the IR signal.
Interesting, thanks for that, no cfl's in the lounge - tungsten & a couple of nifty 1w led golfballs in table lamps. Have cfl's in the next room - horrible things - will see what's switched on when the remote next trips out, no problems since post#19 yesterday.