I used to have an icon on the Windows Vista taskbar showing the battery amount remaining (laptop). It has mysteriously vanished.
How can I get it back?
I followed the Windows FAQ (see How can I hide the battery icon in the notification area? – hoping to reverse the instructions) but the Power checkbox on the Notification Area tab was greyed out and could not be checked or unchecked (it is currently unchecked).
Solution:
I found the solution: Fix Network, Clock, Volume and Power (Battery) System Icons Missing with Disabled or Grayed Out Check Box Options.
In my case I had to delete two settings in HKEY_CURRENT_USERSoftwareClassesLocal SettingsSoftwareMicrosoftWindowsCurrentVersionTrayNotify (see the end of the article).