I am struggling now for last 2 weeks with this funny problem. Calibre v 8.51 works perfectly when I boot my windows 7 pro version safe mode with networking. I can add books from my PC, run in debug mode etc. But when I boot normally, I can not add books, trying to run in debug mode from preference, crashes with error code 5 and 1 coming up

Any idea? I have already uninstalled, re-install 4, 5 times without resolution of this problem. Thanks.