Cannot check in files

I am running the eval version of Vault and everything seemed good up to
the point of checking in files.

We are getting the following message.

"This request requires buffering of data for authentication or
redirection to be successful."

I searched through the list archives and only saw one other post asking
about this issue from back in July of last year and didn't see any
response to it.

Details are:
 
Vault Server is on a Windows 2003 server. Database is SQL Server 2000
and is also on a Windows 2003 server.  (a different  one, but within
same LAN) I am running the Vault Client app on a Windows XP machine also
within the same LAN.

After reading some of the messages I made sure that Anonymous Access is
checked and I am not going through any firewalls.

Any thoughts? I have been trying to get this eval running correctly for
several days and this is the third issue we have come across that has
stopped us.