If you experience some of the following problems:
- Firefox never updates automatically
- When you click from the menu, you get the error message "AUS: Update XML File Not Found (404)"
- Add-ons never update automatically
- When you click from the Add-ons window, you get the error message "Some problems were encountered when trying to find updates."
- You cannot install some add-ons (not all), and you get the error message "The add-on could not be installed because it is not compatible with Firefox.", but you know they are compatible.
These problems might be caused by a program called "TDC Digital Signatur" installed on your computer.
Removing this program will most likely help.
- In Windows, click on the button and select Control Panel to open the Windows Control Panel.
- In the Windows Control Panel, double-click on Add or remove programs.
- In the list of programs, select TDC Digital Signatur, and click .
For more information and options on how to fix this problem while still keeping your digital signatures, please see this Firefox Support page (written in Danish).