vgaarb: this pci device is not a vga device : driver message

I sometimes get this vgaarb: this pci device is not a vga device in dmesg. The screen flashes a lot at boot, and at times I can booted into tty. Then I can ctrl+alt+f7 to get a desktop environment. Output of dmesg:

Any guesses guys? similar problems

Other details:

1. Output of lspci and /var/log/Xorg.0.log .
2. Output of lshw

VGA card:

$ lspci | grep VGA
00:02.0 VGA compatible controller: Intel Corporation Sky Lake Integrated Graphics (rev 07)

OS and kernel:

 ~  lsb_release -a
No LSB modules are available.
Distributor ID: neon
Description: KDE neon User Edition 5.8
Release: 16.04
Codename: xenial ~  uname -a
Linux neon 4.4.0-45-generic #66-Ubuntu SMP Wed Oct 19 14:12:37 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

Since this might be related to nvidia:

~  dpkg -l | grep nvidia
ii nvidia-361 361.42-0ubuntu2 amd64 NVIDIA binary driver - version 361.42
ii nvidia-opencl-icd-361 361.42-0ubuntu2 amd64 NVIDIA OpenCL ICD
ii nvidia-prime 0.8.2 amd64 Tools to enable NVIDIA's Prime
ii nvidia-settings 361.42-0ubuntu1 amd64 Tool for configuring the NVIDIA graphics driver

EDIT: Running a few more times, sometimes it also shows me a segfault which may explain:

Error: 111.183169] sddm[980]: segfault at 40 ip 0000000000000040 sp 00007fff1f7f8b78 error 14 in sddm[400000+6f000]

Output of dmesg: Output of cat /var/log/Xorg.0.log:

Know someone who can answer? Share a link to this question via email, Twitter, or Facebook.