I seem to have stumped both AT&T and Apple with this one. I just upgraded from the 2g to the 3g. My home computer is a g5 tower running osx 10.4. No instructions were received with new iphone, so i swapped the SIM from the 2g to the 3g. Service worked, and was able to sync apps music and video fine, but could not sync contacts calendar bookmarks or mail accounts. I kept getting the following error: itunes could not sync information to the iPhone because anoher sync client is already running I called AT&T and they activated the new SIM and had me swap it back and sync again. Still got the error. Apple hasn't heard of the issue either. I have tried: Full restore of the iphone Restarting my computer Deleting iTunes and prefs completely and re-installing Setting up new user account Latest suggestion (from Apple) is to take it to a Genius store. Has anyone seen this issue before?