I have an old IBM Thinkpad T23 laptop computer. Recently, I have
trouble with the display, black, when I first power up the laptop. After
WinXP boots up, I hold down the Fn key and press F7 (int/ext display)
key to get the display turned on. I often have to do this more than once.

Note: I recently replaced the CMOS battery. I changed the BIOS
(press F1 at power up) setting for "boot display" from "both" to "LCD".

I SAVED the change, but the next time I boot up the T23, I have
the same issue. I reboot the T23 and press F1. BIOS settings, the
boot display is back to "both".

Does anyone know why WinXP changes the BIOS setting?

Thank You in advance, John

My guess is, the T23 doesn't have a working main battery pack
installed in it. When you shut down Windows at the end of the day,
you likely unplug the adapter that is powering the T23 all
the time. This causes the RTC to run off the CR2032 coin cell
until the next morning.

FYI:

You are correct, main battery pack defective, and removed. Note: I
replaced (with 2 AA batteries) the coin battery. This problem started a FEW
MONTHS LATER. It did NOT start right after I replaced the CMOS battery.

Also note: in the battery compartment, I used two NEW AA alkaline
batteries, and this laptop does NOT use a rechargeable CMOS battery.

The original CMOS battery is located in the same area as the main battery.

John