CD key is obviously not valid, thats typically for people with a cracked CD key, they join and get kicked within 30 seconds.
You need to find a way to either get a new one or get your old one back. We cannot do anything about it if your CD key is not considered valid by the taleworld masterservers. Its them who kick you, not ours.
I will ask around if theres something we can do since you actually already owned a valid key once.