Computer will shut down completely for no known reason. Nothing in eventvwr.msc shows anything suspicious leading up to the "Kernel-Power" critical errors.
To Resolve: Edit
1. Check the power connections. Is the computer plugged directly into the wall? Power strip? Try bypassing if so, may be a defective power strip.
2. Shut the computer down and drain the residual power (See "The Dell Fix" For Fan Failures/ Controller Errors) and start diagnostics. If no troubles are detected, call the manufacturer and let them investigate, it's most likely going to be a power supply or faulty motherboard.
3. Check to see if the computer has all of it's hardware drivers up-to-date. Sometimes a new HDD firmware update may be the culprit.