Battery very low - after update ...

Hi,

yesterday I could update my S60 to firmware 4.1, no problem. Before I go to sleep I switch of my S60.
This morning after switching the S60 on, I got the message "Battery very low", but it was 97% loaded. I connected the S60 to the loader, waited till 100% was reached and made a reset, but again the message was shown: "Battery very low". I think, this is an error in the firmware ...