Remote Desktop 3.5.3 problem launching, connecting

I've searched these forums as well as the web, and just can't find anything relevant to this perplexing (and irritating) problem. I have two iMacs running Snow Leopard 10.6.8. The newer one (Core 2 Duo, iMac 10,1) received a clone of the earlier one (Core 2 Duo, iMac 9,1) so I'd expect them to behave identically. Indeed, everything except Apple Remote Desktop does. From the older iMac, I can launch ARD and see the newer iMac's desktop just fine. From either of the two, I can connect to server (cmd-K) and access the other, no problem. But from the newer iMac, I can't even launch ARD normally. Clicking the ARD icon in the dock (or double clicking from the Application folder) causes the dock icon to become active, except the application itself doesn't open until I click the dock icon a second time. That's part one of the trouble. Part two is that once ARD opens, it lists some of the computers on the network but the icons (in the "all computers" listing) are black. Also, it lists itself (newer iMac) but not the older iMac from which everything was cloned over. I've repaired permissions and done a DiskWarrior on both iMacs to no avail. I find myself wondering if the fact that the newer iMac is a clone of the older one has something to do with this, but that's as far as I know how to go. Any and all insight into this will be greatly appreciated, and thanks in advance.