File download failure

I have downloaded files for archive to my PC from my two HDR Fox T2 machines for several years. Suddenly one of them has developed a problem. After pressing "OPT+" then "download", the progress bar comes up with "Unknown time left - 0 bytes" and the blue bar indicates 100%, but no transfer takes place.

This same behaviour happens with some files that have previously downloaded with no problem. The second machine which is set up in exactly the same way still works fine. I am at a loss to understand what is causing this.

Can anyone help?

Web interface version: 1.4.4-1
Custom firmware version: 3.12 (build 3965)
Humax Version: 1.03.12 (kernel HDR_CFW_3.12)
Loader Version: a7.33