80Gb iPod Classic unable to play M4A files from Songbird

Hi there,

I am a new Ubuntu 8.04 user on an x86 Intel P4 processor with 1.5Gb RAM. I recently decided to migrate due to a fall out with Windows. All works well and Songbird (1.0) is a fantastic alternative to iTunes however my (Windows Formatted) iPod Classic, 80Gb, which I restored to factory settings on an XP Machine, does not for some unknown reason want to play .m4a files from my library. The .m4a files play fine on Songbird but once synced to the iPod will not play the files. I would just like to add mp3's play fine still.

I tried reformatting my iPod on my Macbook Pro (Leopard) and it works fine again on there but I then reformat to Windows so I can use on my Ubuntu and the m4a files just will not play once I have synced it to Songbird 1.0

Is this a problem with my installation? Or m4a files? Or my iPod?

Thank you for your time,
Kind Regards,

Xan Manning.