I just ran into something weird.

I have two older computers, an old HP Pavilion, and a homebuilt AMD
system. Both are running Xubuntu 8.04. One, the AMD system, had a 17
inch Samsung LCD screen, the other, the HP, had a 19 inch Samsung LCD
monitor.

Both work well in that configuration, both at 1280x1024 resolution.

Tonight (well, last night), I decided to swap monitors between them.
The AMD system got the 19 inch monitor, and is quite happy with it.
The HP got the 17 inch monitor, and suddenly, even though the same OS
installed from the same CD on the other computer could easily do
1280x1024, all it could now manage was 800x600. It would not offer any
resolutions higher than that.

Since the same OS worked with this monitor before, I decided to try a
"dpkg-reconfigure xserver-xorg" to reconfigure it. It did not work,
ending with an error:

FATAL: Error inserting battery
(/lib/modules/2.6.24-22-generic/kernel/drivers/acpi/battery.ko): No
such device

I might add that neither one of these machines is a laptop.

I searched for this with Google (which, among other locations, found
many hits on the Ubuntu Forums), and found that this is a common
problem, but found no solution.

Anyone have any ideas other than trying a fresh reload? I'm ruling out
the reload for now, as it would take some time to reload all the
packages and home-written software that I have on this machine. I'd
rather just switch the monitors back than do that.