An unexpected restart is a symptom, not a diagnosis.
After Windows starts again, Event Viewer may contain Kernel-Power Event ID 41. Microsoft explains that this event is logged when Windows detects that the previous shutdown was not completed cleanly. [R1]
Event 41 does not by itself prove that the power supply failed, that Windows crashed, or that a driver is bad.
The useful question is:
What happened immediately before the restart, and did Windows record a stop error?
What Kernel-Power 41 actually means
Event 41 tells you that Windows came back from an improper shutdown.
Microsoft documents several different situations that can produce it: a Windows stop error, interrupted power, holding the power button, an unresponsive computer, or a random restart. [R1]
That is why the event should be treated as a marker in the timeline rather than the root cause.
If the same event appears after every restart, do not keep “fixing Event 41.” Look for the evidence that explains why the shutdown was abnormal.
Check whether Windows crashed first
A serious Windows failure can cause an automatic restart and may briefly show a stop code such as MEMORY_MANAGEMENT or another blue/black-screen error.
Microsoft says unexpected restarts with stop errors can be caused by hardware, a device driver, or software. [R2]
When Windows records a bug check, Event 41 can contain the bug-check code. Microsoft also documents Event ID 1001 from Windows Error Reporting as evidence that the computer rebooted from a bug check and that a memory dump may have been saved. [R3]
If a stop code or bug-check record exists, investigate that specific crash instead of treating the restart as a generic power problem.
What if the bug-check code is zero?
A zero bug-check value does not mean the restart was harmless.
Microsoft notes that power can be interrupted before Windows has time to record an error. A zero value can also occur after an unresponsive system is forcibly powered off, and dump-writing problems can prevent useful crash information from being saved. [R1]
Possible causes in this branch include an external power loss, a depleted or disconnected battery, a faulty or undersized power supply, a hung system, or another failure that prevented Windows from finishing its diagnostic record. [R1]
The event alone cannot choose between them.
Look at what happened just before the restart
The events immediately before the shutdown are often more useful than Event 41 itself.
Microsoft's troubleshooting guidance recommends checking suspicious Application and System events before the recorded shutdown time. [R1]
Also note recent changes: new hardware, driver installations, application installations, and Windows updates can be relevant when they appear immediately before repeated failures. Microsoft specifically recommends checking such recent changes when investigating bug-check restarts. [R3]
Timing is evidence of a relationship, but not proof of cause. A driver installed yesterday is not automatically responsible for today's restart.
When should you suspect hardware?
Repeated abrupt power loss with no useful crash record deserves hardware attention.
Microsoft explicitly includes power-supply problems and overheating among the conditions to check when a machine restarts or shuts down unexpectedly without useful bug-check information. [R1]
If the PC is unusually hot, loses power under load, repeatedly switches off without a blue/black-screen error, or shows other hardware warnings, do not assume software repair will solve it.
Back up important data before repeated failures become more serious.
What should I do now?
- Note whether you saw a blue/black-screen stop code before the restart.
- Check Event Viewer > Windows Logs > System around the restart time.
- Find Kernel-Power Event 41, but treat it as evidence of an abnormal shutdown rather than the cause.
- Look for Event 1001 or other bug-check information that identifies a Windows crash.
- Review Application and System events immediately before the shutdown.
- Compare the timing with recent drivers, hardware, applications, or Windows updates.
- If the system lost power without a recorded crash, check power, battery, temperature, and hardware stability.
- If the restart repeats, preserve the stop code, dump information, and timeline instead of making several unrelated changes at once.
- If the machine is overheating, repeatedly losing power, or showing hardware-health warnings, protect important data and investigate the hardware.
The goal is not to make Event 41 disappear. The goal is to determine whether the restart came from a Windows crash, forced shutdown, power interruption, or hardware failure and then investigate that specific path.