Nec ready 120lt problem

I hope this is the correct place to post this. I have a NEC ready 120lt
that is driving me nuts. It has windows 98 and 64mb of ram. It ran for 4
months without a problem. Now , the problem the original user had has re
surfaced.
It shuts down when it feels like it, intermittently, goes dead with no
warning. I have changed all of the possible power up/saver settings, it
doesn't matter if on battery , or another battery, or if the ac adapter
is in use. It does not appear to be heat sensitive. I have re loaded and
updated the OS. It even quit when I was in the bios settings ! Any help
appreciated. Steve.