My previous laptop did not have enough USB2 ports for all my needs.
My Desktop has far too many ports, including two on the "roof" that I can see and easily access on demand.
(My "always needed/available" USB devices like keyboard/mouse/printer and things I forget are somewhere on the back panel)
Macrium created on my secondary internal HDD a partition image backup file of C:\.
I plugged into the rooftop my external backup HDD and used Windows to copy that backup file from secondary to external - no apparent problem.
Then I used Macrium to validate the copy, which would have implied validity of the original.
The copy failed, but I was able to validate the original.
On a rampage I created a new folder on the external and copied the entire set of recent archives from the secondary to the internal.
I think that was probably about 20 GB total consisting of two off 6.5 GB Full images and about 12 off Incremental and Differentials between 300 MB and 1.5 GB in size.
Both the 6.5 GB copies had MD5 errors, and half of the small files also had errors.
I am convinced that although I had properly and fully inserted the USB2 plug into the socket, the connection was defective.
I have subsequently retested and found no problem - I just had a bad connection.
The beauty of TeraCopy is that it does NOT assume the copy is good until it has subsequently read the copy.
It does not CORRECT any error but is guaranteed to detect any MD5 hash checksum discrepancy,
and if need be report the problem and retry a couple of times,
and then allow me to fix any access problems and redo the few that fail.
N.B.
I do not know which of the two ports might be suspect because they are so close together and I failed to note at the time which was in use,
and of course it could be a wonky USB2 plug or lead.
I now am using an eSATA external drive for speed, but again it uses connectors and I still don't trust Windows so I still use Teracopy.