Pen drive transfer to PC corrupting

[janner66]

Recently I have been having problems transferring some MKV files from a USB 3.0 pen drive to the PC internal hard drive. Actually saying that, this is not the issue as they copy over with no evident problems. My mum is saying that when she tries to copy from the internal hard drive to an external hard drive the files are getting so far and just stopping copying. I presume the file is corrupted or is the external hard drive the problem? The external hard drive is probably only a year old. Some files do copy over and some do not. She has Windows 10 on the PC and the hard drives are all USB 3.0. I do copy over the files using USB 2.0 though.
I have not performed any checks on the drives. I don't think the pen drive is the issue as it works on other PCs without any problems.
Would it have anything to do with the PC settings or is it more likely one of the hard drives causing the problem? Thanks.

 

[hang-the-9]

You need to clarify a bit, exactly what is the issue here?

You went from you having issues with MKV files then you say it's not the issue, then it's your mother having the issue.

Start again.

What are you (or her) doing, what is happening? Have you tried different USB ports on the computer? For files that do not copy over, do they copy to any other external drive?