Hi Dave & Leo,
I recall having this issue, years ago, I believe I fixed it by removing the IP from Bindings, Settings -> Bindings, make sure IP Addresses, Ports & Hostnames don't have the old IP listed at all.
Also make sure no domains have the old ip linked to them.
Otherwise, you could edit the xml config files and remove the ip from any of those on the server itself. Stop the server itself first.
It has been a while, so hard to recall what I did exactly to fix it.