If you get this error it means the operating system detected that your GPU have been unresponsive for more then 2 seconds and decides to shut down the graphics driver.
The exact cause is at this moment unknown, and unfortunately it leans towards this being a software/hardware/driver issue that is somehow triggered more frequently when running Vermintide. Following is a couple of things that can be done that has been successful for some users, and not successful for others.
This type of issue is not unique to Vermintide and has been reported by several players of other recent games as well.

Lower your graphics settings
By changing some or all graphics settings some players have stopped getting these errors.

Fullscreen mode is wonky in recent versions of Windows. Better just avoid it all together, Borderless fullscreen should give equal performance as native fullscreen nowdays.

Installing DirectX
The game comes with an older version of DirectX that is supposed to be automatically installed by steam, this seems to fail for some.
You can manually install this redistribution by doing these steps:
  • Right-click on Vermintide in your steam library and choose "Properties" from the meny
  • Goto the "Local Files" tab in the properties view and click "Browse Local Files"
  • Navigate to the "_CommonRedist/DirectX/June2010" folder
  • Run DXSETUP.exe

If you're over clocking your GPU, revert back to stock settings.

Performance enhancing applications
AMD and nVidia both have applications bundled with their driver which hooks into the Direct3D runtimes and tries to apply optimizations for the game.
For AMD this application is called Gaming Evolved, or Raptr, in this writing moment I don't know what the nVidia version is called. Killing those applications have been noted to sometimes remedy the problem.

Nvidia ShadowPlay
Some players have experienced issues with ShadowPlay. This is something we need to investigate. But until then, if you have these issues, try to turn off ShadowPlay.

If you are running a color calibration application called f.lux, it would be wise to shut that down as it has proven to interfere with the GPU in ways that can case massive lag-spikes which potentially could trigger a driver reset.

Finally, there has been speculations that upgrading to Windows 10 from a previous operating systems sometimes messes something up with a couple of timer units in the computer, and this can apparently be resolved by resetting your CMOS to factory settings. There is a thread on the geforce forums that outlines this process, but I would like to stress that this is probably nothing you should attempt if you are not 100% confident in what you are doing. And if you were to attempt this solution it's vital that you follow the instructions and don't skip anything as it could result in even more problems then before.
We at Fatshark can't take any responsibility if anything in your computer would break if attempting to reset CMOS.