Basic Windows diagnostics from the command line — sfc /scannow and Event Viewer
This ties together the whole section — two built-in tools that check whether recurring computer problems share a specific cause in the system.
sfc /scannow — checking system files
Open Command Prompt as administrator
Press Windows, type "Command Prompt," right-click the result, and choose "Run as administrator" — unlike earlier commands in this guide, this one needs elevated permissions.
Type sfc /scannow and wait
The sfc /scannow command checks the integrity of protected system files and automatically repairs any that are corrupted or altered. The scan usually takes a good ten minutes or more — don't interrupt it.
Event Viewer — the system's error history
Open Event Viewer
Press Windows, type "Event Viewer," and open the app. This built-in tool logs the history of every significant system event, including ones not visible on screen at the time.
Check "Windows Logs" → "System"
Filter entries by "Error" and "Critical" level to skip routine information. Entries with a timestamp matching the moment of the problem (a freeze, a blue screen) often point to the specific cause.
How to read the results
- sfc /scannow found and fixed corrupted files — worth restarting the computer and checking whether the problem is gone.
- sfc /scannow can't fix some files — that's a more complex case needing additional tools (like DISM) — a good moment to contact IT.
- Event Viewer shows the same error repeating — a specific, recurring lead for further diagnosis.
When it's a job for IT
A screenshot of the sfc /scannow result along with the text of the most important error from Event Viewer, attached to your report, lets initial diagnosis be skipped and gets straight to fixing the specific, already-identified problem.
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