Haven't tried ethernet because I don't have a router or a switch...

Crossover cable will do (assuming you have an ethernet port on the PC at all). But if, as you said, serial synchs work, then it's not hard disk trouble. Hm.

For the moment, I'm stumped. If you want fast synchs and don't care how you get them, then maybe a crossover cable or a cheap ethernet hub will get you going?