KB00066 - Error 'Unknown' appears when you run Stickies

Symptoms

When you start Stickies, an error appears which just reads "Unknown" (or "Fehlt" if you're using the German language). The app works correctly otherwise. The message may also appear when you access Stored categories in the Manage dialog.

Solution

Run the following command (the location of the file msjtes40.dll may differ on your system):

regsvr32.exe C:\windows\system32\msjtes40.dll

Credit

Thanks to Sooyke for finding this solution.