Ask most Windows 11 users where their PC keeps a record of its crashes and you’ll usually get a shrug. Ask a technician and you’ll get the same answer every time: Reliability Monitor. It’s the most useful diagnostic tool Microsoft ships with Windows, and it’s also one of the best hidden — nothing in the Start menu points at it, and it never pops up when something goes wrong. We open it on almost every laptop and desktop that lands on the bench in Corstorphine because it answers the single most awkward question a customer can ask: “when did this PC start behaving badly?”
This guide walks through opening it on Windows 11, reading the stability chart, decoding the errors and turning that into a sensible plan for what to fix next.
What Reliability Monitor Actually Shows You
Reliability Monitor is a slimmed-down view of the Windows Event Log, focused on stability events — application crashes, Windows hangs, blue screens, failed updates and hardware errors. It plots a daily score from 1 to 10 on a rolling chart, drops icons on the days something went wrong, and lets you click any day to see exactly which event hit the system.
It’s been in Windows since Vista and barely changed since, which is part of why it’s so reliable: there are no telemetry caveats, no cloud sync, no licence prompts. The data is local, granular and impossible to miss once you know where to look.
How to Open Reliability Monitor on Windows 11
There are three quick ways in — pick whichever your muscle memory likes:
- Search: press the Windows key, type reliability and click View reliability history.
- Run dialog: press Win + R, type
perfmon /reland press Enter. - Control Panel: open Control Panel > Security and Maintenance > Maintenance, then click View reliability history.
The window takes a second or two to populate — Windows is collating data from the past year — and you’ll see a chart that looks roughly like a stock ticker.
Reading the Stability Chart
The blue line is your Stability Index. A perfect score is 10, and every event drags it down for the days it’s logged against. Below the line is a grid with five rows:
- Application failures (red X) — a program crashed or hung.
- Windows failures (red X) — an OS component crashed, often a blue screen or unexpected shutdown.
- Miscellaneous failures (red X) — usually power-loss or kernel-power events.
- Warnings (yellow triangle) — Windows Update failed, or a service couldn’t start.
- Information (blue i) — successful installs, updates and removals.
Switch the view between Days and Weeks at the top right. Weeks is the better starting point for spotting a trend; days is where you go once you’ve found one.
Decoding the Reliability Details
Click any day on the chart and the bottom half of the window fills with a list of every event for that day. Each row has a source (the app or component that failed), a summary, a date, an action link and a detail panel. The View technical details link is the gold here — it unfolds the exception code, the faulting module and the stack offset that the Event Viewer would otherwise bury three layers deep.
A few patterns we look for first:
- The same app crashing every two or three days. Usually a corrupt user profile or a stale add-in. We see this constantly with Outlook and Edge after major updates — customers in Newington bring laptops in with the chart showing a tidy weekly pattern.
- Kernel-Power events with ID 41. The PC lost power unexpectedly — loose RAM, a failing PSU, a flaky wall socket. Our hardware upgrades team will reseat memory and load-test the PSU before anything else.
- WHEA-Logger warnings. The CPU or memory controller spotted a corrected error. One is meaningless; a cluster is the first sign of a failing chip.
- Repeated Windows Update install failures. The component store is broken — a quick SFC and DISM run, or a worst-case in-place upgrade, usually clears it.
Spotting Hardware Failure Before It Happens
Reliability Monitor’s real party trick is showing you a problem before it becomes obvious. A failing SSD often shows up as a cluster of application crashes a fortnight before the drive throws a SMART warning — the apps are crashing because their data files are intermittently unreadable, but the disk itself hasn’t hit its threshold yet. Same pattern with overheating CPUs: a slow drift downward on the index, with WHEA warnings appearing as the chip starts retiring cache lines.
If you’re seeing a clear week-on-week decline rather than a single bad day, treat it as a warning shot. A customer in Dalkeith brought in a laptop last month whose index had dropped from 9.5 to 4 over six weeks; the drive failed completely two days later. The chart had been telling the story the whole time.
Acting on What You Find
Once you’ve found the pattern, the response depends on what’s actually failing:
- One app, repeating crashes: uninstall and reinstall it, then check for a vendor patch. If it persists, the user profile may be the culprit — our software troubleshooting team handles this daily.
- Kernel-Power or WHEA cluster: stop using the PC for anything important and run a proper memory and storage test. We do this on the bench with a known-good PSU swap in the loop.
- Windows Update failures only: run the update troubleshooter, then SFC and DISM. Most patch loops clear at that point.
- Generic slow decline with no obvious source: schedule a full health check. A failing drive, a dust-clogged cooler or a swelling battery rarely announces itself politely.
When to Get a Technician Involved
If the chart is showing failures you don’t recognise — or if it’s flat and clean while the PC still misbehaves — it’s time to call in a pair of trained eyes. Customers from Falkirk, Cumbernauld and right across Edinburgh book us in for exactly this: a structured run through Reliability Monitor, Event Viewer and the SMART logs, then a clear recommendation on what to repair or replace. Our remote support team can do most of it without you leaving the desk, and for business fleets our business IT support team sets up the same dashboards across every PC so a developing fault on one machine doesn’t surprise anybody.
Reliability Monitor won’t fix anything on its own, but it will tell you, very calmly, what to fix and roughly when it started going wrong. Once you’ve looked at it on one PC, you’ll find yourself opening it on every other PC you touch.