[daveq]

AJ,
Yeah, I work at a school which has mainly macs networked. Every machine which has been upgraded to OS X often does the spinning ball thing. One of our techs advice was that its partly to do with the way Unix (basis of OS X) looks at information over the network (even when it doesnt have to, it sometimes checks data remotely over the network, even if the current task is all on local drives).
This is not a PT specific issue. It happens in many applications.
Not sure if its related to your prob, but thought disconnecting would answer one way or the other?
dave