Nevermind

Hi jflund, I don't own a Mac, but maybe there is someone who can help you, maybe the people of Ultimake read this forum and come up with a solution for your problem.

I solved it. It seems to be some kind of compatabilty failure. Go to c:\Program files\Ultimaker cura 4.0 or the 3.6 version open it and right click cura.exe choose properties and choose the compatibility tab, check the box in the compatabilty section (run this program in compatability modus for) choose eigther windows 7 or 8 Click the use button below and ok. In my case Cura started without problems. Good luck (I also run it on a windows 10 Pro 64bit version)

I'm curious what happend why did it stop working? I did not do anything, so what caused Cura to behave this way all of a sudden. Couldn't find any help on the net.

Hi, I'm having the same problem. Cura 3.6 was working fine without problems. I ran it yesterday, but got no screen. Nothing happens, task manager shows it's running. Uninstalled it and installed 4.0, but same issue, task manager shows it's runnung but nothing to see. I installed 3.4.1 again, this one is running without any problems. Any suggestions what's wrong? Thanks for any help. Never