I was just wondering if dust is generally a conductor or insulator.
Also, how can dust often cause electronics equipment to malfunction
without usually breaking it completely?
The answers given by other respondents are all spot on...
If you want to see the effects of dust laden electrical components
first hand wait until the first shower of rain after a long dry spell
and stand near a high voltage ac power line. You may hear a continuous
sizzling, spluttering or crackling sound as the high voltage tracks
across the insulators using the moist dust layer as a conductor. At
night time you can sometimes see the blue arcs tracking across the
insulators. That same dust was there in its dry state before the rain
but because it is an insulator it causes no real problems. Add water
and the problems begin - pole-top fires and arc-overs etc.
Power distribution organisations will usually embark on a program of
high pressure cleaning of pole insulators before the onset of winter
to minimise the possibility of hazards from these situations.