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.