This error indicates a problem reading the .cm file from the disk. The file has been found and opened with read access successfully, but the actual read of data from it fails.

If a filesystem check and a surface scan both indicate no errors, then it is possible that some kind of system protection software (e.g. anti-virus, anti-malware) is interfering with file accesses, and this should be temporarily disabled to check if it is the source of the error.