Save Identity Operation Error

I have googled, search Microsoft, and searched blogs and have found nothing
on this error. Any insight would be helpful. Here is the error I am getting
when attempting to login using Domain credentials after successfully joining
a domain.

---Error Message---
Windows Security
The save identity operation could not be successfully completed because the
number of available licenses has been exceeded
---End Error Message---

I don't believe we have exceeded the limit of 25 authenticated Vista PCs,
and we are not yet running KMS since there are only a few of us testing
Vista.

Another wierd note is that I was able to remove this system from the domain,
but the next morning I got the same error message, but this time when I tried
to login as a local Admin account. I restarted and then was able to log in
successfully.

Any ideas on this one?