Thanks Ceel for the reply.
I used the program yumi to put the iso onto the usb disk. Yumi allows multiple linux on the one usb key.
I then tried rufus so Slitaz is the only distrution on the usb key, and tried on a different computer.
I get a message: c32box.c32: not a COM32R image, with boot: underneath it.
I downloaded the rolling version. Did I download the correct one?
I am in the process of downloading a flavor: slitaz-3.0-xvesa.iso to see if this one works.
I have got other distributions to work. Am I doing something wrong or using the program to put the iso onto a usb key?