OK, I see where you were going, asking about AppleTalk, but as I posted above, it doesn't exist in OS X 10.6, so there doesn't seem to be any way that it can be at the root of your issue.
Looks like you'll have to start looking in a new direction, very possibly hardware.
The new Great Equalizer is the SEND button.
In Memory of Harv: Those who can make you believe absurdities can make you commit atrocities. ~Voltaire
