I figure someone else will make this same mistake and need the fix. Situation: MBP 2.16, 3gb Tiger 10.4.10 Office 2004 for Mac Ran Monolingual to get rid of the various languages etc. No problems. Upgraded to Leopard 10.5 Everything worked great... hmmm... need some disk space. Updated Monolingual and ran it. Entourage can't send email, returns error: Unknown Error (-8738) Tried to fix by removing various plists... didn't work. Reinstalled Leopard... that did it. FYI for folks who search on -8738 or (-8738) in the future.