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A colleague of mine has a ThinkPad L560 with an i5 6200U and 16 GB of RAM. Recently, he encountered a problem with it: As soon as the Laptop boots into Windows (not on the BIOS screen!) the monitor turns off, stays dark for a few second, turns on, turns off again etc., rendering the computer totally useless.

As a troubleshoot, I first tried to boot into Windows Safe Mode (The Laptop still ran Win7). In safe mode, everything worked as expected. I therefore thought that it must be a software issue. Since the machine needed an Update anyways, I made a clean install of Windows 10. First, it seemed as if the problem was fixed, I connected it to the Internet and installed some standard software. A few minutes later however, to my utter surprise, the computer made the "device disconnected" sound and the problem occured again. Whenever the computer booted up, it instantly stopped working correctly.

I then tried to boot into safe mode again, which, again, worked properly. At this point, I was unsure wether it was a software or a hardware error. To verify, I used the Display Driver Uninstaller Tool by DriverGuru to remove all display drivers. After that, the laptop booted normally again. The problem reoccured a few minutes later, though. I figured that it might have something to do with the automatic driver installation by Windows Update, so I went under Control Panel -> System and Security -> RAM and CPU Speed -> Advanced System Options -> Hardware -> Device installation settings and disabled the automatic device installation altogether. Unfortunately, that changed nothing and the problem persisted after uninstalling all drivers and rebooting the computer again. When I stop the machine from connecting to the internet, however, the problem does not reoccur, which makes me think that it must have something to do with stuff being downloaded. If I run Ubuntu from a live disk, the computer works as expected.

I really have no idea what to try with this machine anymore. Has anyone ever encountered a similar issue? Is it a hardware issue? Is there something I can install manually?

DLCom
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  • Try the latest drivers [from Intel](https://www.intel.com/content/www/us/en/support/products/88355/graphics-drivers/graphics-for-6th-generation-intel-processors/intel-hd-graphics-520.html), and reboot. – harrymc May 07 '20 at 20:14
  • @harrymc Yes, tried it out, did nothing, unfortunately – DLCom May 12 '20 at 12:50

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Some advice:

  • Run chkdsk
  • Run sfc /scannow and DISM (as explained in the link)
  • Search the Event Viewer for more info
  • Run deep antivirus scans by a couple of reputable antivirus products. If the computer is unusable in the normal mode, try booting in Safe Mode with Network.
harrymc
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  • Thanks for that suggestion, I'll try it tomorrow. However, I highly doubt that it has something to do with the filesystem or malware, as I've already tried to swap the disk and make a completely clean Windows installation. Safe Mode with Network does actually work, but unfortunately not via wireless. – DLCom May 12 '20 at 15:11
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    This might then relate to some installed product. Did this also happen when Windows was in vanilla state? If it did not, then try [this answer](https://superuser.com/a/1531922/8672). – harrymc May 12 '20 at 16:13
  • It did, unfortunately, also happen with a 100% clean and fresh Windows installation without any additional software. – DLCom May 12 '20 at 16:35
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    Have you thought about a hardware error that is only encountered in Windows? – harrymc May 12 '20 at 16:39
  • You're right. That's sadly the most probable explanation. I already tried opening up the machine to check wether there were any loose connections or obvious damage to the PCB's and capacitors, but I found nothing. I'm no Louis Rossman, unfortunately. – DLCom May 12 '20 at 16:42
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    Running [MemTest86](https://www.memtest86.com/) for as long as possible tests RAM, but also indirectly CPU & memory controller. – harrymc May 12 '20 at 16:45