Lyle may be on to something, but I was unable to follow his procedures, and Remote Desktop 3.4 insists that I update my Admin software on my laptop because it finds evidence of 3.5 _client_ software on my computer.
I have client systems that are running 3.4, and I could get reports from them when I was running the 3.4 version of Admin on my laptop. Once I upgraded ARD Admin on my laptop to 3.5, I could no longer get reports from any clients, whether they're running 3.4 or 3.5.1 of the client software.
Regarding Lyle's procedures:
I followed the ARD removal guide on my 10.6.8 admin system (ignoring/replacing the outdated references):http://support.apple.com/kb/HT2577
After uninstalling both the admin and client portions, I reinstalled both 3.4 pieces from the downloads here:
http://support.apple.com/downloads/#remote%20desktop%203.4
1. I don't have a standalone ARD admin system; ARD Admin is installed on my laptop.
2. I couldn't figure out what outdated references to ignore or replace. I just ran the Terminal commands, and everything seemed to uninstall according to plan. Caution: the removal _did_ wipe out my existing ARD database (but that was okay by me).
3. I skipped "unininstalling the client portion" since I'd read elsewhere that it was "part of the operating system" (and thus not removable by casual means). I _did_ shut off Remote stuff in the Sharing preference pane, though.
4. I reinstalled the Admin package from my 3.2 CD, and then updated it with the 3.4 Admin download. When I opened the "finished" 3.4 ARD software, it immediatelyprompted for an update, since it found evidence of a 3.5.x client on my computer. My option was to update, or Quit, so I updated. (Oh - somewhere along the way, I had to re-enter my ARD serial number and (optional) ARD password.
5. I still can't get reports.