Alright, I found a solution myself. It seems to have been a problem with a jogamp-proces.

I found the maplelauncher.l4j.ini in the "bin.win"-folder, opened it with notepad, and added

-Djogamp.gluegen.UseTempJarCache=false

at the end of the file. Then I closed the jogamp-proces manually in the Task Manager, and opened Maple. Succes! :)

@acer That's definitely a nice workaround. Thanks a lot! :)

@acer 

Thanks a lot, that worked perfectly! Just what I was looking for.

Is there a way to do it globally (so it also affects future sheets, or do I have to do it every single time? :)