Duo Performance and lockout

Hi All,

I've been reading up a lot on performance issues that people are having but none seem to quite match mine. I apologise if I've writing about stuff already covered, but the performance troubleshooting page seems to be offline.

So, my setup:

I have a Duo with 2 1TB green caviar drives, running the latest firmware (4.1.13)
This is plugged directly into a netgear gigabit switch (new, problems were already there before)
Network has a squeezebox touch, a WD Live TV, 3 win 7 machines
1 win 7 machine is always on and has a share from the Duo mounted for online backup service livedrive
Duo is running squeezebox

Symptoms:

At apparently random times, playback on squeezebox just stops and it cannot even find the Duo. At the same time I cannot connect to the front end or SSH in or access any shares on the network. If I already have an SSH connection running and it hasn't been disconnected then it becomes extremely slow, but running top shows nothing particularly heavy going on.

Trying to copy files over windows shares is virtually impossible at all times.

Often when transferring large files via FTP, the connection simply closes.

Trying to run IOMeter when this is happening simply says that the share is not available.

Streaming movies over the WD works fine for a bit then suddenly buffering completely stops completely for a few minutes, then sometimes resumes for the remainder of the film.

Solutions tried:

This felt like a network IO problem, so I replaced the switch and cables, but no difference.
I moved the Duo and squeezbox onto the same switch to reduce latency and remove any other devices that might be the cause.

Do I need a new Duo?

Thanks for your help

Ben