Windows 11のエラー修正方法（Windows 11向け）

# Windows 11のエラー修正方法（Windows 11向け）

## Why System Errors Happen — And Why Your PC Is More Exposed Than You Think

System errors don’t just appear out of nowhere. Honestly, they’re usually the result of something specific — a bad update, a corrupted driver, conflicting software, or misconfigured hardware settings. With Windows 11’s global desktop market share now sitting at 72.57% as of February 2026, more users than ever are hitting these exact issues. This guide walks you through the real causes and gives you practical, step-by-step fixes — no tech degree required.


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## Why Your PC Keeps Crashing: The Most Common Errors Hiding in Plain Sight

Here’s the thing — most Windows users don’t realize how many errors are quietly building up until something finally breaks. Windows 11 now holds 72.57% global desktop market share as of February 2026 (StatCounter), meaning millions of people are suddenly dealing with its quirks for the first time.

So what actually keeps going wrong? Let me break it down.

**Blue Screen of Death (BSOD)** is the one everyone dreads. Stop codes like `DRIVER_IRQL_NOT_LESS_OR_EQUAL` or `SYSTEM_SERVICE_EXCEPTION` almost always point to driver conflicts. Microsoft’s February 2026 update triggered kernel-level BSOD crashes (`KERNEL_SECURITY_CHECK_FAILURE`) on gaming PCs with certain GPU setups. That’s not something you caused. That’s a shipped bug.

**Windows Update failures** are practically a recurring event. Error `0x80073712` — meaning update files are missing or corrupted — plagued the March 2026 Patch Tuesday rollout. The January 2026 KB5074109 update caused outright boot loops on commercial machines.

**BitLocker recovery loops** blindsided users in April 2026 via KB5083769 — locking people out of their own data with no warning.

Beyond that, there’s the everyday stuff: **app crashes**, **OneDrive freezes** (Outlook hanging when PST files live in cloud folders), **Remote Desktop failures**, and **shutdown errors** on older hardware that just won’t cooperate with newer builds.

Honestly, what surprises most people is that these errors often aren’t their fault at all. They arrive packaged right inside official updates.


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## Diagnose First: Why Running Event Viewer Before Any Fix Saves You Hours

Most people jump straight to fixes. Big mistake. Honestly, the single most effective thing you can do when Windows 11 throws an error is *identify the exact cause* before touching anything else.

**Event Viewer is your first stop.** Press `Win + X`, select Event Viewer, then navigate to **Windows Logs → System or Application**. Look for red “Error” entries timestamped around when your problem started. Each entry shows a specific error code — that code is your diagnostic gold. Without it, you’re just guessing, and guessing wastes hours.

Safe Mode is the second tool most people overlook. Boot into it by holding Shift while clicking Restart, then navigating to **Troubleshoot → Advanced Options → Startup Settings**, and pressing F4. Safe Mode loads only essential drivers. If your issue disappears there, you’ve immediately narrowed it down to a third-party driver or software conflict — and that completely changes your fix strategy. It’s a step that competitors rarely explain properly.

There’s also **Reliability Monitor** (search “View reliability history” in Start). It charts system stability over time, flagging exactly which app or update destabilized your machine. I think it’s genuinely one of the most underused tools Windows 11 offers — clear, visual, no command line required.

For AI-assisted diagnosis, the **Get Help** app now integrates Copilot-powered troubleshooting flows. Not flawless (I’ve seen it loop on vague errors), but for less technical users it cuts diagnostic time significantly before attempting anything manual.


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## The Proven Step-by-Step Fix Order That Actually Resolves Most System Errors

Here’s the honest truth — most people jump straight to SFC scans without figuring out *what* broke. Don’t do that.

**Step 1: Check Event Viewer first.** Press Win + X, open Event Viewer, go to Windows Logs > System. Filter for red “Error” entries near your problem’s timestamp. This identifies the failing component before you attempt any fix — saves hours of guessing.

**Step 2: Run SFC, then DISM.** Open Command Prompt as administrator and type `sfc /scannow`. Then follow with `DISM.exe /Online /Cleanup-image /Restorehealth`. Microsoft officially recommends this sequence — SFC handles surface corruption while DISM repairs the underlying Windows image.

**Step 3: Review your update history.** Microsoft’s January 2026 KB5074109 caused confirmed BSODs and boot loops on commercial PCs. If problems started after an update, go to Settings > Windows Update > Update History and uninstall the latest cumulative patch.

**Step 4: Boot into Safe Mode.** Hold Shift and click Restart, navigate to Troubleshoot > Advanced Options > Startup Settings. Safe Mode loads only core drivers. If your error disappears there, you’ve got a driver or software conflict — not a corrupted system file.

**Step 5: Roll back the offending driver.** Open Device Manager and look for yellow exclamation marks. Right-click and choose “Roll back driver” or “Update driver.” DRIVER_IRQL_NOT_LESS_OR_EQUAL BSODs almost always trace back to GPU or network adapter drivers acting up after a recent update.


_{Source: https://www.pasoble.jp/imageData/windows11-update-history-check-error-code.gif}

## Safe Mode, BIOS Settings, and the Deep Fixes Most Guides Never Tell You About

When the usual stuff doesn’t cut it, you need to go deeper. Honestly, most guides stop at SFC and DISM — but those won’t help if your problem lives at the driver level or inside your BIOS.

**Boot into Safe Mode first.** Press Shift + Restart, go to Troubleshoot > Advanced Options > Startup Settings, then hit F4. Safe Mode loads only essential drivers — which immediately tells you whether a third-party driver or app is your real culprit. Error disappears in Safe Mode? You’ve already narrowed it down significantly.

**Driver-related BSODs** like `DRIVER_IRQL_NOT_LESS_OR_EQUAL` are surprisingly common and fixable. Open Device Manager, right-click the suspected driver (GPU and network adapters are usual suspects), and choose **Roll Back Driver**. If rollback’s greyed out, uninstall it entirely and grab a fresh copy from the manufacturer’s site directly.

**BIOS/UEFI misconfigurations** trip up more people than you’d expect. Windows 11 strictly requires Secure Boot enabled and TPM 2.0 active. If either’s off — even slightly — you’ll hit errors that no command-line tool can touch. Reboot, enter BIOS (usually Del or F2), and double-check both settings are properly enabled.

Here’s a real-world example: the February 2026 cumulative update triggered `KERNEL_SECURITY_CHECK_FAILURE` crashes specifically on gaming PCs with certain GPU setups (WindowsLatest.com confirmed this). Standard fixes failed completely. The only working solution was uninstalling the patch via **Settings > Windows Update > Update History > Uninstall Updates** — then waiting for a patched rollout.


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## Stop Errors Before They Happen: Maintenance Habits That Actually Work

Here’s the thing — most Windows 11 errors don’t appear out of nowhere. They build up slowly. A skipped update here, a forgotten driver there. By the time your screen flashes blue, the damage was weeks in the making.

So let’s talk prevention. Honestly, this is where most guides fall short — they tell you how to fix errors but never how to stop them from recurring.

**Keep updates on a schedule, not automatic.** Blindly installing every patch is risky. We saw this with the January 2026 KB5074109 update that triggered BSODs on commercial PCs. Check WindowsLatest or Neowin before installing major cumulative updates — it takes 2 minutes and could save you a full recovery session.

**Create restore points before any major change.** Open System Properties → System Protection and create one manually. Takes 30 seconds. Saves hours.

– **Audit your drivers monthly.** Outdated GPU or network drivers cause more crashes than most people realize.
– **Keep at least 15% of your storage free.** Windows needs breathing room for temp files and virtual memory.
– **Disable fast startup on older hardware.** Incomplete shutdown cycles quietly corrupt system files over time.
– **Run `sfc /scannow` monthly** in an elevated Command Prompt — even when nothing seems wrong. Think of it as a routine checkup.

Small, consistent habits compound over time. Fifteen minutes of monthly maintenance is genuinely better than a full day of error recovery.


_{Source: https://www.actualidadgadget.com/wp-content/uploads/2025/03/Error-en-Windows-11.png}


## Don’t Wait for the Blue Screen: Your Windows 11 Health Takeaways and Action Plan

Honestly, if there’s one thing I want you to walk away with, it’s this: Windows 11 errors aren’t a sign your PC is dying. They’re usually a signal that something needs attention — and the earlier you catch it, the simpler the fix.

Here’s a quick recap of what actually matters:

– **Don’t blindly install updates.** January 2026’s KB5074109 triggered BSODs on commercial PCs. April’s KB5083769 forced BitLocker recovery loops on home users too. Always check known issues before updating — or wait a few days after Patch Tuesday.
– **Use built-in tools first.** SFC, DISM, Event Viewer, and Reliability Monitor aren’t just for IT professionals. They’re there for you, no expertise required.
– **Boot into Safe Mode when stuck.** It isolates driver conflicts fast and makes fixes dramatically easier.
– **Check your BIOS settings.** Secure Boot and TPM 2.0 misconfigurations cause errors no command-line tool can touch.

For your ongoing routine, I’d suggest a monthly health check: open Reliability Monitor, scan for recent error spikes, and update drivers carefully with release notes in hand. And back up your data. BitLocker recovery loops taught many users that lesson painfully.

Windows 11 now holds 72.57% of global desktop market share as of February 2026. More users means more patch issues. Staying proactive isn’t optional — it’s part of modern PC ownership. You’ve got the knowledge now. Use it before the next blue screen shows up.