Reliability Monitor gives you a day-by-day stability score and crash timeline built into Windows 11, it’s the fastest first check when a PC keeps acting up or you need to vet a used machine before you trust it.
Open Reliability Monitor
The fastest path is the Run command:
- Press
Windows + Rto open the Run dialog. - Type
perfmon /reland press Enter.
You can also click Start, type reliability, and select View reliability history from the search results. Both routes open the same tool.
Read the stability graph
Reliability Monitor opens to a graph scored from 1 (worst) to 10 (best). Each column is one day.
The graph tracks five event types:
- Application failures: apps that crashed or failed to start
- Windows failures: OS crashes, blue screens, boot problems
- Misc failures: anything outside the other categories
- Warnings: non-critical problems worth watching
- Information (blue dots): successful installs and updates; nothing wrong here
A sharp score drop on a specific date is your starting point. Click that column to see what happened.
Investigate individual events
Clicking a column loads the event list for that day in the bottom panel.
Click View technical details on any entry to see the full error report: faulting process name, exception code, and module path.
Some of that detail points you directly to a driver or app. Other entries are less actionable on their own, but patterns across multiple days matter more than any single event.
Assess what you’re looking at
A handful of red X marks scattered over a month is normal. Even stable Windows 11 machines log occasional application failures, and a bad shutdown shows up as a Windows failure without meaning the system is unstable.
Watch for these patterns instead:
- The same app crashing on multiple separate days
- Several Windows failures in a short window
- A score drop that lines up exactly with a Windows Update or driver install
- Warnings that appear repeatedly and never clear
If you’re evaluating a used laptop or refurbished desktop, check the full 30-day timeline. Isolated events are fine. Clustered failures, especially back-to-back Windows failures, are a red flag worth investigating before you commit. Frequent Windows failures alongside blue screens can also point to a failing SSD or a bad RAM stick, which is worth ruling out before you dig into software fixes.
Check the full problem report list
Click View all problem reports at the bottom of the Reliability Monitor window.
This flat list is easier to scan when you’re looking for a specific app or want to see repeated failures grouped together. Sort by Problem to stack identical crashes in one place.
Go deeper with Event Viewer
When Reliability Monitor flags an event but the technical details aren’t enough, Event Viewer has the full raw log. Press Windows + R, type eventvwr, and press Enter.
The Summary of Administrative Events section groups errors by count over the last 24 hours, 7 days, and 30 days. Double-clicking an entry opens the complete log entry, including the event ID and source, which is what you need when searching for a specific fix.
Conclusion
Reliability Monitor solves the “when did this start going wrong?” problem better than any other built-in Windows 11 tool. The perfmon /rel command gets you there in seconds, and the timeline does the filtering for you. If the last few weeks show mostly blue dots with the occasional blip, the system is in good shape. A tight cluster of red failures that started on the same day as a driver update or new software install gives you a concrete starting point instead of guesswork.