SE K600i and Bluetooth Headset Issue

I have a recurring problem with my SE K600i (also affects my K608i) and
a Nokia bluetooth headset.

Whenever an incoming call is received, the headset takes at least four
or five seconds to wake up and start playing it's own ringtone. When I
press the answer button, it takes a further four or five seconds before
it starts transmitting audio (however the phone has already answered so
the caller is already hearing audio from my side).

This is a bit annoying, to say the least!

Does anyone else experience this problem, and know of a solution?

Archive searches and a look on the SE support website have proved
fruitless. I've tried resetting the headset completely and removing the
pairings from both the headset and the handsets concerned.

Thanks.