How I fixed a freezing Windows 7 laptop

HUGE DISCLAIMER: for all things you're trying because of this blog post, please be aware that I do not take any warranty whatsoever. Because fixing my computer is not my business.

Despite the disclaimer, here's the story how I got a arbitrarily freezing, completely unusable Window 7 laptop working again.

Please note that I write this article mostly for selfish reasons – just in case I'm pleased to fix something similar in the future. So don't expect a nicely written article with no spelling mistakes etc.

But still, it might be helpful for you if you sit in front of a frozen Windows PC yourself at the moment.

The Symptoms

Got approached by my neighbor with a 5 year old Samsung laptop with a conventional harddisk built in. Strange thing was that the laptop started reasonably fast and I was able to pass login. However, after a few minutes the PC froze entirly.

  • The screen was left as is, so no blue screen
  • No response to anything I did with the mouse or the keyboard
  • Only way to bring the system down was a hard shutdown with on/off button
  • Running the system in Windows protected mode worked just fine
  • According to the LED, harddisk was busy all the time
  • Heck I wasn't even able to launch Task Manager or Resource Monitor
  • Waiting for 15 to 30 minutes brought back the PC for a short period. Got frozen after that again.

I figured that it might not be a software problem. Seemed that there was something wrong with reading and writing from the harddisk.

First thought: I needed to get Resource Monitor launched.

The Things I Tried

Here's what I tried in mostly chronological order.

Uninstalling Norton 360

  • Sometimes I managed to launch Task Manager and saw that Norton's n360.exe was on top of the list most of the time.
  • Uninstalled it by launching in protected mode
  • After launching in normal mode, things were getting a bit better

Was is it a software problem against my initial suspicion?

Running AdwCleaner and Malwareytes

  • Laptop was also used by kids. So a lots of "free" games, YouTube downloaders and stuff.
  • Malwarebytes found about 1.500 threats. Here's a German instruction on how to use MalwareBytes.
  • AdwCleaner reported about 250 problems.

The result: laptop was still freezing. Hardware problem?

Would running disk fragmentation solve issues?

  • Checked if contents on disk was heavily fragmented. Nope.

Monitoring harddisk usage

  • Back to my harddisk problem suspicion
  • Due to less weight on the system through removing malware and Norton, I was able to launch Windows Resource Monitor
  • Resource Monitor can be launched via Task Manager's performance tab.
  • It allows to see which processes are accessing the harddisk and how the performance thereof is.

Strange harddisk behavior

  • Response time of harddisk reads and writes was constantly extraordinary high in the ranges of 5.000 to 50.000 milliseconds
  • Sometimes the disk utilization plot showed nothing for a while
  • Compared to disk utilization metrics of my own laptop (also no SSD, d'oh!): response time was around 50 to 80 milliseconds while working

Running good old MS DOS chkdsk

  • Started a Windows command prompt and ran chkdsk in various configurations
  • No problem found

Booting laptop in Windows repair mode

  • Hitting F8 while booting to bring up Windows boot menu
  • Ran memory diagnosis from repair menu, no problem detected

Making a backup of user data

  • In case I would have to reinstall Windows on C:
  • I hate it when people store their data on the Windows partition

Running Samsung Recovery

  • In my case had to hit F4 in the very beginnging of booting up to enter recovery
  • No options there that would help me to diagnose hardware problems

Check if harddisk runs in PIO instead of DMA mode

  • Explanation PIO vs. DMA
  • DMA ... Direct Memory Access, no CPU power needed
  • PIO ... Programmed Input/Output, involves the CPU and is considerably slower
  • Wasn't able to quickly find information about that
    • Wanted to check in Device Manager, but laptop was freezing all the time
    • As far as I remember, wasn't able to spot this information in Windows protection mode too

Uninstalling Intel Rapid Storage Technology

Checking harddisk drivers in Device Manager

  • Everything up to date

Searching for a tool to check the physical health of harddisks

  • Stumbled upon this German YouTube video explaining harddisk diagnosis with Ultimate Boot CD
  • With Ultimate Boot CD you're able to boot the PC from an USB drive or a CD and run various computer diagnosis tools

Running Samsung ES-Tool to check harddisk health

  • Samsung ES-Tool comes with Ultimate Boot CD
  • There we go: check reveals about 10 bad sectors shortly after starting the check
  • Let the check finish. Took about one and a half hour (500 GB harddisk capacity by the way)
  • Against my expectations, no more than those ten bad sectors were found
  • Conclusion: backing up files earlier was a good thing.
  • Concern: will I have to waste even more hours into solving my neighbor's computer problem?

Remembered that I read somewhere that Windows would be able to detect bad sectors and avoid writing stuff into it.

This Solution (In My Case)

  • Looking how to do that with Windows. Here are instructions from Microsoft
    • Open Windows Explorer
    • Right-click the partition you want to check, e.g. C:, and select Properties
    • In the dialog, choose Tools
    • Click the Check now... button in Error-checking
    • In Check disk options choose Automatically fix file system errors and Scan for and attempt recovery of bad sectors
    • Hint: For the partion the OS is installed on (i.e. most of the times C:) you can only schedule the check to run at next startup
  • Running check for partition D:. No problem detected.
  • Running check for partition C:. Leaving the laptop alone, doing some programming stuff. Missing when check was finished, thus no clue what the check did.
  • Using the laptop for a few minutes. Everything is fine. Considerably good performance when launching Word and browsing the web.
  • See what Resource Manager has to say about harddisk utilization metrics.
  • Wow, response time is in a normal range.
  • Working with PC for a few more minutes. Computer seems to run fine!!

Ploblem fixed?

  • Used the laptop for the next two days.
  • Was never freezing again.

What's next?

  • Setup of CrashPlan to have a decent backup solution in place in case the harddisk will fail some day in the future.


Hope this article serves me well the next time I have to fix a freezing Windows PC.

Until then, hope it was helpful for you too.

Published by Robert Möstl

« Back to Blog