Setting Up Dynamic ClusterCATS Fail-over with CF 4.5.X on NT4.0/NES
When clustered with CF 4.5.x using static IP addresses, ClusterCATS IP Failover causes an Address conflict when the failed server recovers until it reboots and clears the IP conflict. This URL goes into considerable detail about how and why the problem occurs and how to detect and prevent it.
Setting Up Dynamic ClusterCATS Fail-over with CF 4.5.X on NT4.0/NES