Shut Down Automatically

Dell Vostro 3400 been using for 4 years always shut down automatically recently. Pre-boot System Assessment Build 4126 has been running automatically very frequently before starting laptop.

Run startup repair, 

Diagnosis and repair details:

Root cause found:

Unspecified changes to system configuration might have caused the problem.

Repair action: System Restore

Result: Failed. Error code = 0x1f

Repair action: System files integrity check and repair

Result: Failed. Error code = 0x490