Hi there. I have an odd problem with my D40 where if I leave it switched off for a couple of hours it won't switch back on again until I use the hard reset button in the USB compartment.
After a reset the camera can be switched off and on again no problem. But leave it a while and it's dead again.
I've tried a new battery and cleaned the lens/SD Card/battery connections with IPA.
Anyone had a problem like this? It's really frustrating