Error: There is a problem with the file and it cannot be copied

Question

I've been trying to copy (and essentially move) the contents of an NTFS-formatted external HDD to my iMac's internal HDD so I can then format the external HDD to Mac OS Extended. However, when I simply try to drag and drop, I get an error during the transfer that states:
There is a problem with the file and it cannot be copied.
I tried a basic cp command in Terminal to copy all contents of the external HDD to a folder on my iMac's desktop, and found that while there were no errors, there were many individual files missing full chunks of data (ie. original file would be 4GB on my external HDD, but only 350MB on my desktop).
Any ideas on how I can successfully copy a large amount of data (approx. 170GB) from my external HDD to my internal HDD while avoiding this error, so I can ultimately format my external HDD to Mac OS Extended? ANY help is greatly appreciated.

Answer 1

That's not a good error to see. It indicates something is very wrong. Pulled out of an old programming header file:
ioErr = -36, /*I/O error (bummers)*/
If Apple labelled it "bummers," they had a good reason! Unfortunately, that doesn't bode well for you.
Try running Disk Utility again. Keep repairing over and over until one of two things happens: 1) Disk Utility says no repair was needed, or 2) Disk Utility reports the same error in two sequential repair sessions and is unable to repair it both times.
If you hit the second case, or if you hit the first but still can't copy files, then you've got two basic options:
= Buy a third-party disk utility or two and try them. Try TechTool as a first choice.
= Recover what files you can and write the rest off as gone.
= Send your drive to a data recovery service and hope they can extract more than you can.
Of course, none of this is necessary if you have a backup of the contents of that hard drive. (If you don't, this is your learning experience. Once bitten, twice shy, so they say.) Also, regardless of the outcome, once you've got your data or have decided it's gone, you're going to want to wipe that drive completely clean. Reformat the drive with Disk Utility, then when it's done, select the drive in Disk Utility and hit command-i. (Don't select the new volume you just created on that drive, select the drive itself. Mine looks like "232.9 GB Hitachi ..." with the volume name indented underneath.) Look for an item that says S.M.A.R.T. Status, and if it doesn't say Verified, you might as well throw out the drive. Don't trust any more data to it.
If all appears safe, you can start moving data back onto it. But, as always, make sure you have a backup of everything!