This is one for us all to put in memoryMikeMail wrote:
And immediately realized that (boy, this is stupid) my window panels had been scrambled so that most of the capture panel was stretched way to the left, behind the preview panel. The real solution was settings > Layout settings > Switch to > Default, and all the right capture options were back.
Thanks loads to all who helped with this. Lessons learned - check your layout and forget about USB.
Glad it's sorted, happy editing.