Airtunes hangs when time machine starts

Hi,

I have got one time capsule with one airport express. On snow leopard (10.6.2), I've configured time machine on time capsule. As soon as time machine starts (every 1 hour), airtunes hangs. I guess this is due to some QoS misconfiguration. But I haven't found anything about it. Does anyone has got any idea/fix to limit those hangs ?

Regards
Marc