This is not just a network issue. It affects my Mac even when sharing on local drives. I am, however, bound to an Active Directory and logged in as a "mobile" account.
The question is, Adobe: what is a good workaround, and why can't you trap for this and steer the program in the right direction? That would be very helpful. For example, if you try to save to a network resource, you could pop up a diaglog that says, "Hey, don't do this, because there's an OS bug and Photoshop will do very bad things". ...???