ATI Radeon 9660 and TV out

Hi Folks

I have installed build 5308 (Beta 2) of vista onto a test system with an ATI
Radeon 9660 graphics card with latest drivers from ATI.

The issue is, when the PC is switched on I get output to both TV and Monitor
(Mirrored) as soon as Vista hits the graphical interface I loose TV output.
If I disconnect the monitor and boot only with TV connected, again I loose TV
output as soon as it hits the graphical user interface.

Regardless of resolution and setting (That I have tried!) in the Catalyst
drivers once Vista hits the graphical interface I can not get any output to
TV.

This is a test Media Centre PC so TV out is quite important ;-)

I am using composite out.

Any ideas?

Cheers
SuperPlay