I am trying to help a friend with a clean reinstall of Windows XP "SP1a" (The
Windows disk that came with the computer) on a Dell Dimension 8400.  I’ve run
the BIOS setup routine so the computer boots first from the CD drive.  When
the computer boots with the Windows disk in the CD drive, I get the following
message: “Press any key to boot from CD.” (You have five seconds, or it boots
from the hard drive.) I press spacebar and the Windows setup routine starts.  
(This is important; it shows the keyboard is working.) There are messages
that a lot of drivers are loading.

Then I get this message:

“Welcome to Setup.

“This portion of the Setup program prepares Microsoft® Windows® to run on
your computer

“To set up Windows XP now, press ENTER.”

I press ENTER and nothing happens.  I’ve tried the other alternatives (R and
F3) and nothing happens.  Nothing happens with Ctrl-Alt-Del.  Obviously there
is a failure of keyboard input.  I’ve duplicated this with both the Dell’s
wireless keyboard and a wired IBM keyboard, both connected through a USB
port.  When I boot Windows from the hard disk, both keyboards work fine.

There is an available update to the Flash BIOS (optional per Dell’s
website), but I hesitate to apply it because I smoked the motherboard of this
same friend’s Gateway trying to update its BIOS (under warranty, so we’re
still friends).

BTW, Windows setup on the CD will not run from the Windows environment
because the computer has been updated to a “newer version of Windows,” i.e.,
SP 2.  It forces you to do a clean reinstall.

Any help would be greatly appreciated.