Blue Screen of Death — What It Means and What to Do
Windows is working away happily. Then the screen goes blue, a sad face appears, the PC reboots itself, and you've lost whatever you hadn't saved. That's the Blue Screen of Death (BSOD). Windows saying "something went wrong at a level I can't recover from, so I'm restarting before anything else breaks."
A single BSOD isn't the end of the world. Repeated ones mean something's wrong and the PC is trying to tell you about it.
What the Blue Screen Actually Says
Modern Windows BSODs look something like this:
0% complete
If you'd like to know more, you can search online later for this error:
The important bit is that line at the bottom: the stop code. That's your clue. "MEMORY_MANAGEMENT" means something went wrong with RAM (or the software managing it). "DRIVER_IRQL_NOT_LESS_OR_EQUAL" points to a driver problem.
The Stop Codes Worth Knowing
You don't need to remember them all. But if you see the same one more than once, what it's called tells you where to start looking.
| Stop code | What it usually means |
|---|---|
| MEMORY_MANAGEMENT | RAM problem, or a driver talking to RAM badly. Run a memory test. |
| DRIVER_IRQL_NOT_LESS_OR_EQUAL | A driver is misbehaving. Often recent GPU, network or audio drivers. |
| SYSTEM_SERVICE_EXCEPTION | Usually a driver or antivirus clash. |
| CRITICAL_PROCESS_DIED | A core Windows process crashed. Often disk corruption or malware. |
| PAGE_FAULT_IN_NONPAGED_AREA | RAM, drive, or driver. Common after a RAM upgrade gone wrong. |
| KERNEL_SECURITY_CHECK_FAILURE | File system corruption, driver, or hardware. |
| WHEA_UNCORRECTABLE_ERROR | Hardware error — usually CPU, RAM or overheating. |
| IRQL_NOT_LESS_OR_EQUAL | Similar to the driver one — often faulty RAM or a bad driver. |
| UNMOUNTABLE_BOOT_VOLUME | Your drive is dying or the file system is corrupt. Don't ignore. |
| INACCESSIBLE_BOOT_DEVICE | Drive or controller issue. Often disk-related. |
If the BSOD is about the boot drive, that's urgent. See my guide on what to do when your drive fails before the PC gets worse.
The Five Real Causes
Underneath the scary codes, BSODs boil down to one of five things:
1. A dodgy driver
Graphics drivers, network drivers, weird USB accessory drivers. Classic pattern: BSODs started happening shortly after you installed a new device, or shortly after Windows Update pushed a new driver. In Device Manager you can sometimes roll back the driver to the previous version.
2. Failing RAM
If you keep getting MEMORY_MANAGEMENT, IRQL, or PAGE_FAULT errors, run a RAM test. Windows has one built in: press Windows key, type Windows Memory Diagnostic, run it and restart. It'll test the RAM on boot. For a more thorough check, MemTest86 on a USB stick is better but takes longer.
3. Overheating
If the PC always crashes during heavy use (games, video editing, Teams calls) or on hot days, it's probably overheating. WHEA_UNCORRECTABLE_ERROR especially points this way. See how to stop your laptop overheating. On desktops, it's usually dust in the heatsinks.
4. A failing drive
Bad sectors, corrupt file system, or a drive on its last legs produce errors like CRITICAL_PROCESS_DIED, UNMOUNTABLE_BOOT_VOLUME, and INACCESSIBLE_BOOT_DEVICE. Back up now, then investigate. CrystalDiskInfo (free) will show you the drive's SMART health in a few seconds.
5. Software conflict
Usually antivirus. Two antivirus programs installed at the same time will fight, and Windows will crash. Uninstall any extras and let Windows Defender do its job. See my post on whether you actually need antivirus.
What to Check First, In Order
- Has anything changed recently? New software, new hardware, new Windows Update, anything in the last couple of days. If yes, start there. Uninstall the new thing or roll back the update.
- Run Windows Update. Sometimes the fix is already waiting.
- Check Event Viewer: press Windows + X → Event Viewer → Windows Logs → System. Look for red "Critical" entries around the time of the crash. They'll often tell you which driver or file was involved.
- Run the memory diagnostic. Takes 15 minutes and will rule RAM in or out.
- Check SMART on your drive with CrystalDiskInfo, or the built-in command: open Command Prompt as admin and type
wmic diskdrive get status. Anything other than "OK" is bad. - Check temperatures. If the fans are noisy and the laptop is hot to touch, that's your answer.
- Run SFC and DISM, Windows' built-in system file repair tools. Open Command Prompt as admin and run
sfc /scannow, thenDISM /Online /Cleanup-Image /RestoreHealth.
When One BSOD Becomes a Problem
A single, one-off BSOD might just be a bad driver update or a cosmic ray. Don't panic. But if you're seeing them:
- More than once a week
- With the same stop code each time
- During the same activity (boot, gaming, waking from sleep, printing)
- Accompanied by other symptoms (noise, heat, slowness)
Then something specific is wrong and it's worth diagnosing properly. Left alone, BSODs tend to get more frequent, not less.
If your PC won't even boot after a BSOD, I covered that in what to do when your PC won't turn on. And if heat and fan noise are part of the picture, why your PC is so loud covers the hardware side. More general troubleshooting in common PC problems.
Mark has been fixing computers since the late '90s and went self-employed in 2008. Based in St Helens since 2013, he works evenings and weekends from his home in Laffak — friendly, affordable repairs for PCs, laptops, and Macs. See reviews on Google
Keep getting blue screens?
Bring it in or let me come to you. I'll read the crash logs, test the memory and drive properly, and find what's actually causing it.
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