ASUS U56E Laptop Rebooting Issues

I have an ASUS U56E laptop that has an issue with random restarts.

By that I mean that I can boot the laptop and it will boot fine and anywhere from 1 minute or more the laptop will reboot itself. It always reboots fine.

I have tried to narrow down the issue but haven't found anything to completely solve the issue.

I have noticed there is a chime of some sort just before it shuts down.

I disabled the internal network card and used a USB network adapter and that lessened the frequency of the shutdowns, but they are still occurring,

After disabling the internal netwark adapter and using the USB network adapter I can boot and leave the system idling (doing nothing) that it does not reboot. If I then start browsing with Firefox it will eventually reboot itself again.

I"ve checked the Event Viewer and there are several entries for Kernal Power. Image attached.

Not sure where else to look to see what is causing the laptop to reboot.

Any suggestions or assistance would be appreciated.

Well that might be a little difficult as this laptop is 4 to 5 years old. So returning to ASUS probably won't fly.
I appreciate your response though. May be time to look for a replacement laptop.

Thanks again