Chosen Solution
I cannot download it. The system is struggling but not successful. IS there any file damaged? Update (10/07/2015) My iMac is using Intel i5. I think the main problem may be the damaged Disk Utility? But how to mend the file?
The highest system a G5 will go to is 10.5.8 Leopard. Anything above that requires an Intel Processor.
You may need a better network connection. Try waking up early in the morning or very late at night when there are fewer people online. You also may have issues within your own system. Do you have enough free space on the drive? Did you first run Disk Utility to check it out?
