I have downloaded the mac "locomotive" many times and receive a "codec overrun" error. I am at a loss. I have read that this means a damaged .dmg, Any help is appreciated.

  Machine Name: iBook G4   Machine Model: PowerBook6,5   CPU Type: PowerPC G4 (1.1)   Number Of CPUs: 1   CPU Speed: 1.2 GHz   L2 Cache (per CPU): 512 KB   Memory: 768 MB   Bus Speed: 133 MHz   Boot ROM Version: 4.8.7f1