Mounted Drives Cause Applications to Hang on Connection Change

Question

When I change from wired to wireless connection to my network (or vice versa) mounted volumes seem to cause applications using those volumes to hang. This happens when going from wired to wireless, or vice versa, and happens regardless of the path (wired + wireless -> wired; wireless -> nothing -> wireless; wireless -> wired, etc.). Affected applications do not recover until the original connection is restored. Un-mounting all Volumes before switching prevents this problem. This problem causes the Finder to hang if an unmount or browse of a mounted volume is attempted after the switch.
(All volumes are on the same network on the same workgroup as the affected Mac. Wireless is via an AirPort Express connected to the same router as the Mac.)
MacBook Pro (15.4"- 2.33GHz - 3 GB - 160 GB)   Mac OS X (10.4.8)   (Macintosh 128k, long ago)

Answer 1

Well, maybe Windows has a hook to explicitly "turn off" a network interface, which shuts down the TCP connections; and maybe OS X doesn't have this.
It should be "a long time" (on the order of 10 minutes), not forever.
I think that unmounting prior to the switch is the only way to prevent this. If there is another way, it probably involves using ifconfig in Terminal to force the old interface down (which might explicitly tell TCP to give up on the old connections).
Powerbook G4 1GHz   Mac OS X (10.3.9)