System shuts down randomly, and doesn't happen at the same time or under the same circumstance, so truly stumped by this one.  Often happens a couple of minutes after boot, other times when the battery is approaching full charge.  Have tested power cord and battery, reseated all components, cleaned with compressed air and replaced memory and hard drive, but to no avail.  Also updated to latest BIOS, but problem still occurs.  Any thoughts on what's going on?

Thanks for any help you can provide.