Using 4.3.11(?), I was just greeted with this message. It comes up within a small Audio Engine window I think. Sorry for being vague, I’m not currently at that specific machine. This message did not affect Dorico (much?) when closed from the window’s x button, everything just worked (apart from the playback I think). I pushed on because I needed to quickly do a lead sheet, and didn’t troubleshoot much.
Restarting did not fix the issue. There was also a windows update that took place just before the issue.
Could you point me to a general troubleshooting direction, so that when I get home I can get straight to it?
The audio engine itself does use skin files. I would suggest you try reinstalling Dorico itself, which will reinstall/repair the audio engine if need be.