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?
