Apple Logic Pro /LogicExpress Discussion

Hey,

      My G4 won't recognize my firewire any longer?  All my Logic work is on external 
drives.  

      My G5 laptop however still sees the drives.

      So, do you think it's a bad connection port?  Or is it that once you use a drive with a 
newer Operating System, that the older operating systems don't recognize the drive any 
longer???

      Appreciate any wisdom on this!!