If you're maintenance is up to date, you might need to contact Altiris/Symantec to see if they have something for you.
In the future, though, I would create a backdoor local account in DS that you can get into in these situations.
To do this, you would click on "Tools" and then click on "Security".
Under manage users you would click "Add" and then create a local, or "DS", account. Make sure to add it to any appropriate groups. That way if something ever happens with your domain (whether the name changes, domain controllers go down, etc.) you have a backup way of getting into reset the rights.
Sorry I couldn't be of more help though.