Just installed CC3 3.01, tried it on 2 computers, same behavior - launches with default project, prompt for sign in (doesn't matter if I try to sign in or not - which btw, always fails if I try to sign in, also reallusion hub always says fails to connect to internet eventhough not true), then sits there for a few minutes than whole window blows up and process gone.

Spec for computer 1:

Windows 7 x64, 32 GB RAM
Nvidia GeForce GTX 1060 Driver 25.21.14.1634 (DX11 compatible)

Spec for computer 2:
Windows 10 x64, 32 GB RAM
Nvidia GeForce GTX 1080 (DX12 compatible)

No issues found running DXDiag on both computers.
Both OS updated to the latest....computers should meet the spec you provided.

Once saw a DX error in Windows Event log, but most times no error at all to trace from, just poof and gone.

Don't know what to tell, can't even run your product...