I looked to battc.sys and CmBatt.sys and installed the latest versions and now all is ok!!!
This should have advised me the Dell service specialist, instead offering a new battery.
Thanks.
I just have the same problem with my Dell Latitude D410:
In BIOS Battery Info: Battery not installed. And also the batterypower window says no battery.
Dell told me, that I should buy a new battery. But the battery works normal with...