'Unexpected error' when copying a cub file from a TM1 backup

[djs]

On a nightly basis, we backup the contents of our TM1 server's Data directory to a zipped folder whose name contains a datetime stamp. Occasionally there's a need to copy the contents of this zipped folder to a new TM1 model for testing purposes. A recent folder backup contained 485 files. When I copy the contents of the folder to the Data directory of a new model, 484 of the files copy successfully but a file called tp_Planning.cub has issues. I get a window that says:

An unexpected error is keeping you from copying the file. If you continue to receive this error, you can use the error code to search for help with this problem.
Error 0X80004005: Unspecified error


Other cub files that are larger than this one are being copied correctly. Since the file is in a backup location, it's just like any other file and I'm thinking this should not be a TM1 security issue. When I copy tp_Planning.cub by itself without it having ever been zipped, I still get this error.

Any ideas on what I can do to get past this issue?