I have a problem that has just appeared recently.  If I am using battery power and then decide to plug-in the machine will work on AC, but will not recharge the battery.  If I reboot the computer then the battery will be recharged.

 

I have multiple batteries and AC adpaters (all from Dell) and this problem occurs with all of them.  Swapping batteries or AC adapters does not help.  Rebooting does.