Dell Dimension 2100 System Reference Manual page 18

Recovery mode from
BIOS failure.
Microprocessor has
failed a BIOS test.
Memory failed to be
sized or enabled.
If the problem persists,
see "Contacting Dell"
in the Solutions
Guide for instructions
on obtaining technical
assistance.
Set the configuration
jumper to Maintenance
mode, and restart the
computer. Enter
thesystem setup
program and ensure that
the processor speed is
set correctly. Exit and
save the setting. Turn off
the computer, reset the
configuration jumper to
Normal mode, and then
restart the computer. If
the problem
persists, see "Contacting
Dell" in theSolutions
Guide for instructions on
obtaining technical
assistance.
If the problem persists,
see "Contacting Dell" in
the Solutions Guide for
instructions on obtaining
technical assistance.
Reseat the memory
modules. If the problem
persists, remove all but
one memory module,
and then restart the
computer. Repeat this
step until the
malfunctioning memory
module is identified.