What I found is that if I record the greeting and then listen to it before saving it will play. It will then give me the error when I hit "Save". If I record it and then "Save" it without listening to it, it will "Save". I could then listen to it after it was saved. Easy fix but seems like an odd glitch that they should fix.
Thank you, thank you, thank you. This worked beautifully, and is much easier than having to take my phone to the AT&T store to reset it, which I have had to do repeatedly, as this is a company phone which I do not have the password for.