If the first launch dialog is present on an ARD client, a "Copy and Open" or Open Items task may fail.
The reason this happens is that when an application is launched for the first time, Mac OS X asks the user to confirm opening it for the first time as a security measure.
After the confirmation dialog appears, opening a file that uses this application will succeed when the user confirms by clicking the Open button within a specified amount of time.
If that doesn't happen soon enough, the task will eventually time out with this message:
"A communication failure occurred with this computer."