I struggled for a long time with v4.0 of the Palm Desktop software - my Palm has v3.5.3 of their software, and I have the USB connect kit. I could not get it to work via the ports on the back of the Mac or via those on the keyboard. Finally, I tried the two USB ports on the back of the LCD display -- and it works passably. If the Palm fails to sync, I swap to the other USB port and the problem clears immediately. I have to change ports about ever five to six synch operations. But at least it works.
I sure wish some bright person would solve this issue -- it's clearly a bug. My money is on Palm, as they've been lukewarm at best to Mac support. I think it's purposeful to force users to pay for the next upgrade.
[robg adds: I haven't had any synch issues, either with my previous Palm IIIx nor my current Tungsten (the cradle is plugged into an eight-port USB hub). Can anyone confirm the problem, and more importantly, that using the LCD USB jacks on an Apple monitor may fix the problem?]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20030529121024223