some regmon observations: activating the check-mark to show the battery icon on XP: (show) 3.73006361 rundll32.exe:1384 SetValue HKCU\Control Panel\PowerCfg\GlobalPowerPolicy\Policies SUCCESS 01 00 00 00 00 00 00 00 ... 3.73007492 rundll32.exe:1384 SetValue HKLM\Software\Microsoft\Windows\CurrentVersion\Controls Folder\PowerCfg\GlobalPowerPolicy\Policies SUCCESS 01 00 00 00 01 00 00 00 ... 3.73040393 rundll32.exe:1384 SetValue HKCU\Control Panel\PowerCfg\PowerPolicies\3\Policies SUCCESS 01 00 00 00 00 00 00 00 ... 3.73041290 rundll32.exe:1384 SetValue HKLM\Software\Microsoft\Windows\CurrentVersion\Controls Folder\PowerCfg\PowerPolicies\3\Policies SUCCESS 01 00 00 00 02 00 00 00 ... 3.73051596 rundll32.exe:1384 SetValue HKCU\Control Panel\PowerCfg\GlobalPowerPolicy\Policies SUCCESS 01 00 00 00 00 00 00 00 ... 3.73052478 rundll32.exe:1384 SetValue HKLM\Software\Microsoft\Windows\CurrentVersion\Controls Folder\PowerCfg\GlobalPowerPolicy\Policies SUCCESS 01 00 00 00 01 00 00 00 ... 3.73427506 rundll32.exe:1384 SetValue HKCU\Control Panel\PowerCfg\CurrentPowerPolicy SUCCESS "3" 3.73450186 explorer.exe:1136 SetValue HKCU\Software\Microsoft\Windows\CurrentVersion\Applets\SysTray\Services SUCCESS 0x1F deactivating the check-mark to show the battery on XP: (hide) 4.20495390 rundll32.exe:1384 SetValue HKCU\Control Panel\PowerCfg\GlobalPowerPolicy\Policies SUCCESS 01 00 00 00 00 00 00 00 ... 4.20496517 rundll32.exe:1384 SetValue HKLM\Software\Microsoft\Windows\CurrentVersion\Controls Folder\PowerCfg\GlobalPowerPolicy\Policies SUCCESS 01 00 00 00 01 00 00 00 ... 4.20528861 rundll32.exe:1384 SetValue HKCU\Control Panel\PowerCfg\PowerPolicies\3\Policies SUCCESS 01 00 00 00 00 00 00 00 ... 4.20529756 rundll32.exe:1384 SetValue HKLM\Software\Microsoft\Windows\CurrentVersion\Controls Folder\PowerCfg\PowerPolicies\3\Policies SUCCESS 01 00 00 00 02 00 00 00 ... 4.20539970 rundll32.exe:1384 SetValue HKCU\Control Panel\PowerCfg\GlobalPowerPolicy\Policies SUCCESS 01 00 00 00 00 00 00 00 ... 4.20540875 rundll32.exe:1384 SetValue HKLM\Software\Microsoft\Windows\CurrentVersion\Controls Folder\PowerCfg\GlobalPowerPolicy\Policies SUCCESS 01 00 00 00 01 00 00 00 ... 4.20898665 rundll32.exe:1384 SetValue HKCU\Control Panel\PowerCfg\CurrentPowerPolicy SUCCESS "3" 4.20923207 explorer.exe:1136 SetValue HKCU\Software\Microsoft\Windows\CurrentVersion\Applets\SysTray\Services SUCCESS 0x1E