FredF

Yes, I have setted Update automatic, so this could be the case. I setted system restore point again. This settings was lost after I installed Windows again in January.

Thank you for your reaction IHaveNoName and BoltBait! This afternoon I installed Paint.net 4.1.4 again and now the problem is gone! I really don't know what went wrong. When the problem occured I scanned my computer at once with Kaspersky and MalwareBytes, but nothing was found.

I don't know. A year ago I installed it too without problems

It was a modified Firestorm viewer for Second Life / Opensim

When I start Paint.net version 4.1.4 and select Ctrl-O ( open file) the program does not react anymore. When I select a file and choose open with paint.net, then I can modify that file in Paint.net and save the file. PdnRepair.exe did not solve the problem. The problem started after I installed something. Uninstalling of that program did not solve the problem. Versions 4.0 and 4.12 I can't use on the same reason. Version 3.5.11 works good. But there the functionality is not as good as in the 4.1.4 version. How can I solve this problem??