This is caused by a faulty registry setting. Do the following:
- Start up regedit (Start > Run > "regedit"), then navigate to the following key: HKEY_CURRENT_USER\Software\vso\ConvertXToDVD\settings
- Highlight this key and delete it
Please note that this will revert all your settings back to default. All settings that might have been customized before need to be set again.