This problem had better be fixed in the OS X version of their software. I currently synchronize my Palm IIIxe (which has a serial cable) through my Keyspan PDA adaptor with Entourage (and Quicken) in Classic mode. I am having the same problem in Classic as I did in OS 9.x: often when I sychronize, the sychronization program either fails to start or starts and stops, not allowing me to synchronize. The only somewhat reliable fix is to open up the set-up app, disable synchronizing, unplug the Keyspan adapter form my hub, plug it back in, and re-enable synchronizing.
I do not know if this problem is the fault of Palm's software or Keyspan's drivers, but it has annoyed me ever since I got my B&W G3 years ago (I never had the problem using Palm's serial adaptor and my PowerMac 7600). Has anyone else had this problem? Does the same problem exist with the Palm USB adaptor?