System Image and error 0x80070015

[Penmere]

I went to windows 10 from windows 7 a few months ago and all went well.
Lately however I have not been able to create a system backup. I get the message "The device is not ready. 0x080070015".
I have tried using both of my USB hard drives and get the same message.
I had previously created a system repair disc, but when I try to boot from it, all I get are the four blue squares. Nothing else.
When I now try to create another system repair disc, I am told that the files are not available, and I must insert the installation disc, but I do not have one.
I would be very grateful for help.

 

[Penmere]

I went to windows 10 from windows 7 a few months ago and all went well.
Lately however I have not been able to create a system backup. I get the message "The device is not ready. 0x080070015".
I have tried using both of my USB hard drives and get the same message.
I had previously created a system repair disc, but when I try to boot from it, all I get are the four blue squares. Nothing else.
When I now try to create another system repair disc, I am told that the files are not available, and I must insert the installation disc, but I do not have one.
I would be very grateful for help.

 

[Penmere]

I am replying to myself because I need to add the fact that both my USB hard drives are behaving normally as far as file explorer is concerned.