No, this is not the problem, if I turn of the PC for the night, the error appears the next day too. Only steam and the editor are running. I even use the microsoft repairkit for the .NET framework.
THEN I FOUND THE ISSUE!
Make sure, the *.locdb is NOT opened in your preview window!
The *.locdb is located in the treeview, where you can find the mod-image.
