Sound Intermittent/ broken up on start up

[Sweaty1]

I have just recieved my Sony 43X4309C and I am using the Optical output to drive my Logitech surround system.  With settings to PCM everything worls fine.  However when turning on the TV the next day the sound is broken up and intermittent until I cycle the speaker settings from Audio out to TV and Audio output to 'Auto 2' the back to PCM.  Is there a fix, workaround or setting change i need to make.  If not it's going back!

Thanks for any suggestions

[Sweaty1]

Update.  i can now only get optical output consistant if i restart the TV, either by turning off at the wall or using the power button on the back.  Surely this is not normal!!