Hi Jan!!!! First of all I want to thank you for your help. I downloaded the new version 5.21, I do not see any error window but I did not work any of the tabs above, both Windows and the others. I had the window in grey completely without any options menu. I was checking TLS 1.2 in the Internet Explorer Web browser settings and it was enabled. Finally I realized that I had the old version of Internet Explorer, specifically version 8.0, then I downloaded version 11.0. Once updated Internet Explorer to version 11.0 now works correctly Heidoc software as you can see in the next screenshot. Thank you very much for this great software. Greetings from Spain!