Can't get newly-installed Adobe InCopy to open/create files

I have a user's computer which I upgraded the OS on (10.4.11 to 10.6.5), and afterwards I went to check to see if InCopy runs. It couldn't open any files. After awhile, I realized that it couldn't do File->New either. If I open a file, spinning beachball of death. If I launch the app without a file, I can wander about the menus fine, until I do File->Open, which brings up an OpenPanel, or File->New which brings up a panel with some page configurations. As soon as I click on the "OK" or "Continue" button in one of those panels, it's over -- spinning beachball, with Force Quit the only way out. So

I started over -- ran uninstall and install -- here is what I have done:

1. Ran the uninstaller, ticking the remove preferences option.
2. Put all remaining InCopy files that I could find in the trash, emptied the trash.
3. Ran the CS5 cleanup tool which I found on the adobe support site. (It cleans up CS3 and CS4 installs, too.)
4. Looked around for Library/Preferences/Adobe/In Copy is root Library and each user's directory, trashed everything.
5. Used applejack to fsck the disk, repair permissions, clean system and user caches, clean up virtual memory.
6. Rebooted, logged in to an administrator account, ran the "Setup" program inside the InCopy installer. Put in the license number, set it to install everything on the list (recommended).
7. Used Get Info on the /Applications/Adobe In Copy folder to set its permissions and the permissions of all files down the tree to read+write for everyone.
8. Launched InCopy, Clicked on File->New and hit "Continue" on the panel. Program hangs.
9. Force Quit InCopy.
10. If I use AdobeUpdate to Update to 6.0.6 I get exactly the same behavior.
11. If I update to 6.0.5 I get the same behavior.
12. If I try to open an existing InCopy file, it hangs the same way.
13. Enabled the root account repeated the entire rigamorole as root.
14. Deleted In Copy and associated files as root, installed as administrator.
15. Try running as root and as (non-privileged) users.

My own computer runs InCopy just fine, giving these messages to the Console:

1/21/11 3:34:24 PM [0x0-0xaa5aa5].com.adobe.InCopy[43770] Error in XmlRpcClient::writeRequest: write error (error 32).
1/21/11 3:34:51 PM Adobe InCopy CS4[43770] * __NSAutoreleaseNoPool(): Object 0x3618180 of class NSCFArray autoreleased with no pool in place - just leaking
1/21/11 3:35:40 PM [0x0-0xaa5aa5].com.adobe.InCopy[43770] virtual uint32 XMLRPCIdleTask::RunTask(uint32, IdleTimer*) threw -18151471 (feeb07d1) 'Failed executing externalEditor.registerEditor'

I can watch the Console on the machine where IC hangs, it gives all of those expected Console messages, until I go to open the file, and there are no messages after that.

Anybody have any clue as to what I've broken? We have InCopy alone or InCopy as part of the whole CS4 in multiple machines, and everyone else's works just fine.