Second Superdrive glitch

For some strange reason, when an audio CD is in the lower of the superdrives, when i play it iTunes, there is a small glitch for a second in the audio of the first track. It's very strange ?

Anyone else experiencing this ?

 

I updated the superdrive Pioneer DVR-111D I bought additionally to 1.29 Firmware

The one that came with the machine is AB09 ? I cant seem to find this anywhere and the pioneer 1.29 firmware updater wont recognise that drive ?

Strange.

It's only iTunes that exhibits this problem with the lower superdrive. Like I say just for a split second at the start of track 1 on an audio cd it glitches.

Additionally - should the drives be left at cable select / or should i make one master & the other slave ?