I have the same problems, too. sometimes it works sometimes it doesn't.

I have noticed (while connected with HyperTermin) that everytime the connection gets killed, I have tons of this messages on the serial port:

endpoint stall(clear stall on ep4)
endpoint stall(clear stall on ep5)
endpoint stall(clear stall on ep4)
endpoint stall(clear stall on ep5)
...

I don't know if this might be somehow related

btw, I also have a PJB100, which also syncs over USB and it has been working flawlessly.

edit: how comes there are two different usb drivers in c:\windows\system32\drivers (RIOHD.sys and empegCar.sys), which are both identical except for the name?

Marc