Stop UE from crashing

I am using UE 4.12 and it often crashes when I try to drag recources from the content viewer to the main scene. It wouldn’t be bad, but it also crashes the whole system, even mouse pointer doesn’t move. I tried to launch it with sandbox, but it crashed the sandbox and the system. I tried to launch it on Virtualbox, but it didn’t work because of DirectX was incompatible. While I was writing this message, I tried to open the project, but it crashed the system at starting.

What should I do with this? Maybe, somebody knows where the code opening .uasset files is stored?

Typical error messages:
Ensure condition failed: false [File:D:\Build++UE4+Release

  • 4.12+Compile\Sync\Engine\Source\Runtime\Core\Private\Misc\ConfigCacheIni.cpp] [Line: 3338] &nl;Scalability.ini can only set ECVF_Scalability console variables ('r.TranslucentLightingVolume'='0' is ignored)
  • Assertion failed: NumElements > 0 [File:D:\Build++UE4+Release-4.12+Compile\Sync\Engine\Source\Runtime\Core\Public\Containers\ContainerAllocationPolicies.h]