Win98 shutdown, by itself

Recently bought a compaq with 98 SE factory installed. It seems to shutdown by itself and restart. Runs the scandisk each time because it shuts itself down improperly. Recently removed the lithium battery and reset BIOs. Seems to have slowed down the number of times it shuts down. Compaq tech support says to check the “disable fast shutdown” in MSconfig(general advanced section) which does not exist. Anyone else have this problem ore suggestions. I have already check power sources, connections, cards and switched surge protectors.