I originally had a 4 port passive USB hub plugged into one on mu USB ports on my MOBO. The other USB port on my MOBO (I only have two) was where the iPac plugged in.
I had the trackball and spinner both plugged into that hub.
My guess is there was not enough power going to the USB hub, but not really sure. I read in these forums several other issues that got traced to that problem.
My CP is removable, so I didn't want to plug the trackball and spinned directly into the MOBO since it's not accessible from the front. That's what the hub was for.
My solution was two parts, and not elegant, but it was cheap and it worked.
1. I had a USB-->Ps2 adapter sitting around, so I plugged that into my iPac cable and then plugged the iPac into the PS2 Keyboard connector on my MOBO.
2. I had two usb extension cables, so I extended the lentgh of each of the trackball and spinner cables. The extensions run from the MOBO up to where they are accessible from the front of the cabinet when I want to change my CP.
It left a lot of extra cable laying around since the existing cables on the spinner and trackball are already pretty long. So it's ugly but it works.