Cannot get battery/powermeter icon to stay in taskbar on laptop

I am running Windows XP Home, SP2 on my laptop. The icons for "on ac power", "on ac power/charging" and "battery - __%remaining" -- in other words, all the power management icons -- will not stay in the taskbar. I have tried going to control panel>power options>advanced tab and checking box "always show icon on the taskbar". It will take, but when I reboot, icon is gone. I have tried applying it and locking taskbar --same thing. I have gone into taskbar properties>hide inactive icons>customize and marked "always show" for "On AC Power". The next reboot, icon is gone.
I have done a repair of "systray.exe" using my XP Home disk. That brought back an old icon that had long ago disappeared -- my Synaptics Touchpad icon. On the first reboot, both this and the power icon disappeared again. Any help in getting the battery power meter to stay displayed would be appreciated.

 

Where did you first start seeing this problem. Did you change anytjing,

 

I'm not sure if it coincided with update to SP2 or not. Since it's a laptop, there were no hardware changes made. All AV scans (avast and trendmicro's on-line) come back negative.