VoiceAttack configuration data is stored in a config file under %localappdata%\VoiceAttack.com rather than in the registry.
The profile database and its backups can be found under %Appdata%\VoiceAttack
Try moving the VoiceAttack.com folder to a safe location, and starting VoiceAttack again.
If it starts after doing so, attach the user.config file to a post here, as it may be useful in preventing such an issue in the future.
Otherwise, try the same thing with the folder containing the profile database.