Prior to continuing, it would be prudent to make sure the issue you are encountering is not occurring as a result of an application conflict. The best way to proceed would be to try loading under a new Window's Administrator account and in a "clean boot" state.

Create a new Windows Administrator (<--important that its an Administrator) account:

Windows 10\11:
http://windows.microsoft.com/en-us/windows-10/create-a-local-user-account-in-windows-10

Log in under that account and try. If it fails, and while still under that account, please click the link below for performing a 'clean boot' under it:

https://support.microsoft.com/en-us/kb/929135

After you've loaded Windows in a clean state, please try once again. 

Purging game installation

Purging Game Installation \ Reinstalling

Please uninstall GC4 from Epic Library:

...