C810 mouse problem after bios reset

Hello

I've searched thru the forums and other help, but can't seem to find an answer, so I hope someone will be able to help.

I have a Latitude C810 laptop - yes, I know it's old, but it still works very well for what I use it for,

It's set up to dual-boot either Windows XP Pro orUbuntu, and until yesterday I had no problems at all.

However, I took out the removeable battery, and when I replaced it and powered on, I was warned that the date and time had been reset.  So my assumption is that the BIOS backup battery is done, and the BIOS config had been reset.

After powering on and booting, I discovered that the touchpad was no longer working, whereas it had been ok prior to the BIOS reset.

Using Windows XP, I could use only an external PS/2 mouse, but not the touchpad.  Using Ubuntu, I could use neither the external PS/2 mouse nor the touchpad (I could use an external USB mouse though).

So, it's not an operating system driver problem, I'm assuming it's a BIOS config problem - but what setting was changed?

I have the mouse bios setting set to "Touchpad - PS/2 Mouse" so I assume that's the setting to allow either/both.  But it still doesn't work./

Any ideas?

Thanks for reading!