I've been battling an annoying problem with Apple Remote Desktop (ARD) where it crashes when you click on the "scanner" icon to run a scan of the network. Several searches had been unproductive until I found this article in the knowledgebase today. The thing is that even though it has "crashes" in the title a search for crash and the ARD product won't show it. Once you click scanner you have just a second when the program opens to move it back to "master list"... but that is a tiresome work around.

So the hint says you can only have 29 network ports in your active configurations. This means you can't have more than 5 "locations" set in network preferences because there are some ports (internal modem) that even if you don't use you can't delete.