I used UNetbootin to install Puppy on USB stick, this time allowing UNetbooting to download and install the version in its menu rather than select the one I downloaded that's stored on my hard drive.

I have changed the boot menu to boot from USB+anything before any other options, but I cannot boot to this stick. It's the same as with the hard drive that I had connected via a USB cable:

"Media test failure. Check cable."

I have trawled forums, but they are all too advanced and discuss problems related to Puppy already being used, not those related to trying to get a glimpse of it X-( ?:|