In some rare case you may get the error "Root element is missing" when Yadis! Backup is starting.
This is due to the config file which got corrupted.
Here is how to solve this issue:
1) Shutdown Yadis! Backup
Go to the system tray, right-click on the Yadis! icon and select "Shutdown".
Click "Yes" in the warning popup box.
2) Go to the folder C:\Users\[username]\AppData\Roaming\Codessentials\Yadis
You need to replace the [username] with your username.
3) Delete the file "Yadis.xml".
4) Rename the file "Yadis.xml.tmp" to "Yadis.xml".
5) Restart Yadis! Backup and verify all your settings.