An experienced and very knowledgeable Pentax user who has a K-m dropped me an email for a strange problem he had encountered recently, quoted:-
"I am using Eneloop with my K-m. If the batteries are shown 1/2 full and I tried to do sensor-cleaning/mirror-up, sometimes it will try but display a blank screen then exit & back to normal shooting mode. Sometimes the camera will reset itself completely w/o mirror up. Sometimes it will do mirror-up then reset. This only happens when the battery is shown 1/2 by the camera, never when full. The camera supposed to show a message if not enough power for sensor cleaning, but rarely does. I have tried different sets of Eneloop and setting the battery type to AUTO & NiMH with the same behaviour. Is your K-m doing the same?"
So, I have just tried. In the beginning when the "half-depleted" is first shown, there is no problem. However, if more power is drawn from the Eneloops (say, by firing the camera in the continuous Hi mode), whilst it will still show the yellow "half-depleted" symbol, but then everything will happen exactly as what are described above by that user, and the sequence is the same, too! And at last, my K-m was reset and every setting including the date/time and file number were erased! :-(
Well, this bug is actually rather stupid and it has never been seen before for other Pentax DSLRs that I owned. I still remember that my *ist D and DS would show a warning message for sensor cleaning when the battery power was not adequate. Too bad..
As a general reminder and recommendation of mine, do never try to clean the sensor when the battery level is shown to be just lower, which might be dangerous and would cause damage to the shutter mechanism when the shutter and mirror are "suddenly" closed.
Having said that, the above bug found is actually rather silly and ridiculous. It shows how careless and casual those Pentax firmware programmers were or how hurry they might be when the firmware needed to be "finalised".
So, after all, will there be a firmware update? Any? Nope? Never? (for an "old" product which may reach the end of its product cycle soon)