I've had the same problem (presario 2100) and it looks like updating the
bios can somehow kill the bios. I don't know why Hp/Compaq didn't warn
us all of this darn predicament, specifically of this model and the like.
Anyway here's what you can do as a last resort if nothing else can be
done. You'll have to change the bios-chip which is located in one of the
panel-board opening for your min-pci wifi card at the bottom of your
laptop. Unscrew the panel and you'll see beside the wifi card a very small
ic-chip known as your bios-chip. If you don't know how to extricate this
chip ask someone who knows how to do it for you. Anyway, most likely
the specifications for your chip are as follows:
PLCC BIOS Chips 1
VERSION: Default
ModelNO: Compaq Presario 2100US
Extra_Info: 32 pin PLCC
MBMFG: COMPAQ
BIOSCHIPDATA: SST MPF 39SF040 70-4C-NH
Go to http

/biosman.com/ and with the info above order a new chip to
replace your old one. My Presario 2100 now works after a long time of
not having a working bios chip and knowing I should never update the
bios, for good.
RMTZ
sunset_drv@yahoo.com