excel "thisn prg performs illegal operqation"

[-----nks-------]

my pc has the following configuration
win98se
celeron 1000
ram 512
hd 50 GB

i use MSoffice 2k profesional
i had no problems
suddedly excel crashes and shows the message

"this program perform an illegal operation and will shout
down"
and
in details says
"
excel caused general fault in module user.exe at
0003.00003d32
register....
"

all the other programs word, outlook,.. work perfect

i uninstall all the office and i install it three times...
nothing changhe word,... works perfect but ecxel crashes
all the system

i change the ram i update the windows nothing


can u suggest smthng


thnks

nks

ps/ i try to avoid to format all my system