Logic Pro 7, AUDIO PROBLEMS ( I'M NEW TO MAC/LOGIC) Options

[PAUL R]

I am a pro musician who records rock music and Tv programme music - after lots of trouble with my PC and Cubase for seerals years , I finally made the move to MAC !! I got a new POWERFUL G5 (2.5 - 3meg ram) and Logic with a MOTU 24/io card... new pci card and drivers,so far,so good !! Its early days ( I've only been set-up 3 weeks) but one major niggle has appeared : I record audio in 24 bit resoloution and check the audio window and all files are present and correct at 24 bit but when I close a song/project down and re-load it,some of the audio files will not re load back into the song - desribed as being '8 bit and unplayable thru coreaudio' !! THESE FILES show as blank regions - I gotta say I'm frustrated by this as overall the new system is EXCELLENT - I am slowly working with apple support's help- but as yet no luck with resolving my problem !! I have as yet to figure if this happens randomly to audio tracks or possibly to ones I have copied and pasted within the arrange page.. either way when I have to re record guitar / vocal parts as they do not re load I'm not a happy bunny !!

ANY HELP ADVICE APPRECIATED - Paul