RightFax RPC error on TCP/IP

I have a client with a Windows 2000 based network. There are 4 win2k servers and one older NT4 server. One of the Win2k servers is running RightFax 8.0 and Exchange 2000. The server is ntsrvmail. Rightfax was on for 6 months prior to adding Exchange2000. After adding Exchange 2000 everything was working fine for about 6 months. RightFax was using TCP/IP. Sudenly, and I mean suddenly, any time a client workstation chooses the FaxUtil they get the following error:

RPC Authorization Error 1722occurred on binding ncacn_ip_tcp:ntsrvmail[1053}

I have search the Rightfax Knowledgebase, Technet, and have even uninstalled RightFax and reinstalled fresh. The data was pilled from backup.

Thanks in advance for any help.