Cannot copy files to, rename or unmount external HD

Question

When I try to copy files to my 4TB Mac Os Extended(journaled) G-drive connected via Firewire 800 I get this message "The operation can’t be completed because an unexpected error occurred (error code -50)."
When I verify the disk itself(the orange disk with firewire symbol) in disk utility, it checks all the normal parts of the file structure and volume information this volume in disk utility then disk utility says "The volume GEE-THAT'S_BIG appears to be OK." I get the same report ""The volume GEE-THAT'S_BIG appears to be OK." when I verify the mounted volume in disk utility. When I try to repair either the disk itself or mounted volume I receive this "Error: Could not unmount disk".
When I try to eject the disk in Finder I receive this error message "The disk "GEE-THAT'S_BIG" wasn't ejected because one or more programs may be using it". This happens even when the only application I am running is Finder.
If I try to rename this disk I receive the "This name can't be used    Try using a name with fewer characters, or with no puctuation marks" error message (even though the orginal name I gave this disk and the name it reverts back to has punctuation marks).
I believe I'm getting this problem because of corrupted permissions. Why are the Verify Disk Pemissions and Repair Disk Pemissions greyed out for this disk in disk utility? What can I do to resolve this issue?
thanks,
Tim

Answer 1

I simply switched the Firewire daisy chaining between my 1TB external and this 4TB external. Problem solved...