The system rebooted without cleanly shutting down first

What it means

Windows restarted after losing power, freezing, being held off by the power button, or crashing.

Why it matters

Repeated 41s point to power, overheating, hardware or driver problems.

What to do

• Look for a 1001 BugCheck around the same time (a blue-screen crash).
• If there’s no BugCheck, check power supply, UPS and temperatures.

Find it with PowerShell

Get-WinEvent -MaxEvents 20 -FilterHashtable @{
  LogName = 'System'; Id = 41
} | Select-Object TimeCreated, ProviderName, Message

Add -ComputerName SERVER to query another machine. Other event sources can reuse the same ID number, so check the ProviderName column.