Help just tried to boot from usb

[bpalstatt]

Hello all real rookie here just install FreeNas to a 8 gig USB. Boot to it from my laptop worked so i then went to the computer i want to use as the server plugged USB in booted this computer a starts to boot but stops at not UFS next line no/boot/loader next line default:0fd(0,a)/boot/kernel/kernel and it just sits at this line and does nothing. this is my first attempt to set up a server please help this rookie....