I have a strange situation where the 'on AC power' tray icon is constantly re-appearing on each fresh boot.

I can go into the power settings in control panel and uncheck 'always show icon in taskbar' but it resets on reboot.
I think it's most likley a registry setting somewhere, but I'm not sure where the key in question is located.

Has anyone seen this problem before? and can anyone point me at the registry key in question so I can disable it.

Just for info it's an XP pro SP2 install.