I have been running Server for NFS for over a year now. About every 5-7 days
the Service seems to become unresponsive. I start noticing "Unable to Update
Mapping" errors in Event Viewer. If I try to restart the Service, the
Service Hangs and then the OS (2003 ST. R2) becomes unresponsive. This would
leave me to beleive this is not a mapping problem (don't use the mapping
anyway), but it is a problem with the Service. Once the Server is rebooted,
it works for another 5-7 days. I have tried to run this Service on 3
different Servers with the same result.

Currently Using:

MS 2003 Server ST. R2

Server for NFS 3.5

Any ideas?

You should uninstall SFU 3.5 from an R2 server and install the built-
in Server for NFS service and see if that shows the same problem.
Check this out on how you can install that -
http://blogs.msdn.com/sfu/pages/introduction-and-installation-of-services-for-nfs...

- Ashish