The only thing I could think of, as an alternate source of temp information, was to restart the system after it had been on for a few hours and go immediately into bios and look at the temps provided in the HW Monitor tab.

Well, fans were reported as doing roughly the same speeds as reported by lm-sensors, and the cpu temperature is reported as 43C.

So I guess its a matter of not worrying about it, and maybe in some update at some point it will get fixed.

Thanks. Its good to know that others get similarly erratic results from lm-sensors, so its not just me doing something stupid!

Peter