Just be sure I understand.
1.. You download the minime.iso.
2.. You start up Live USB creator and install the downloaded "untouched" minime.iso directly to your USB stick
try to use the download in any way on your system first. If the install to USB is successful then you can start thinking about "modifications" or customisations. My impression was you would try and customise first before loading it onto the USB???
The failure of djohnston
suggested run set me back, I did not expect that would have failed. The figures you provided in my suggested test told me you did not have anything "leftover" in /temp or /root/tmp and in general it looked healthy from a size point of view.
I was not fast enough, djohnston beat me comfortably:
Aaaaahh ummmm as you can see we have your interest at heart and want to nail this problem. My particular interest is the USB stick (but unlikely to be your problem). What a laugh we may have at the end