The local policy Allow Access to this computer from the network is

I have gone into the subject policy several times and added groups and
updated the policy. However, without fail, after about 3 minutes, the local
policy with the Allow Access to this computer from the network is reverted
back to being blank. What is causing this? And, how do I get the policy
change to "Stick!"

Thanks,

Carl

Background informaion: This is on a standalone W2k3 Ent. server with sp1
and all patches. The server is NOT part of a domain. Normally you would
expect to see a fairly long list of users/groups in this security policy
setting such as IUSR_YOURSERVERSNAME, Users, etc.