File Copying Problem iMac27

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I recently bought a new iMac27. I have an ioSafeG3 2TB external
hard drive that I back up my files to.

Where I am having a problem is backing up my images folder
to my hard drive. After adding images to my folder I will drag
the image folder over to the external hard drive icon and copy
over the old folder. I have done this for over a year with my
old iMac20, no problem.

Now when I do this I get this error message --

The operation can’t be completed because an unexpected error occurred (error code 0).

If I change the name of the image folder by adding a character or number
to the name of the folder, then I can copy the folder to the external
drive. It is when I try to copy over the folder with the same name
that I get the message.

I read some some stuff on forums about erasing and reformatting
the external drive to Mac OS Extended (Journal) format and I did
that. It still gives the error message.

Any help will be greatly appreciated.

thanks kindly, Chris

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