I'm thinking that your system does not like the USB drive. Can you install the ISO on either a different USB Flash drive or try the install using a different computer? If it were me I'd use a computer which has a CD drive and burn the ISO to a CD, then install ONLY the SSD in the computer and bootstrap the CD, install FreeNAS, reboot to ensure FreeNAS does boot properly, shut it down and move the SSD to the correct machine, boot up and ensure it works.
Have you run MemTest86 and a CPU Stress Test on this machine yet to ensure it is stable?