We have seen this in the past sometimes where the OS reports a conflict with a MAC address that is actually the address of one of the cards on itself.
Normally IP conflict detection on Windows is done by performing an ARP lookup for the IP address the machine is about to assume - if it finds another machine makes a response to the ARP query (used to look up the ethernet address for a given IP address), then it assumes that its IP address is in conflict with the machine that answered the query.
Our network driver does nothing to ARP but snoop on it to learn IPs, and occasionally make requests, but it makes no replies, which is why I always found this issue very difficult to explain, neither have we ever seen it in testing.
It shouldn't create too many problems, since normally what happens is the other machine gets its IP address disabled, and since there isn't one, there is nothing to disable.
You could however try downloading the 5.0.8 version we just released. It is available on our website at
www.wingate.com (if that gets redirected to Deerfield.com, then try
www.netpatrol.com)
Adrien