Can't boot 'kernel' message when trying to boot from USB .

[Sopalajo de Arrierez]

I have installed pfSense on a AMD64-X2 computer without problems, but this time I am testing on an older machine (512MB RAM), and my attempts to boot from MenStick USB version always stop at the beggining , with just a message:

Can't boot 'kernel' 

No more error messages, just the usual stuff of "Booting … etc".

I request some help, please. How can I boot (and thus install) pfSense when this error happens?

Of course, I can write down any additional info, but isn't it possible to obtain more data of the problem than such a simple error message?

These are the versions I have tested (created with Rufus):

pfSense-memstick-2.3-ALPHA-amd64-20160101-0738.img
pfSense-memstick-2.2.6-RELEASE-i386-20151221-1450.img
pfSense-memstick-2.3-BETA-i386-20160117-0430.img

[Sopalajo de Arrierez]

Answering myself: solved booting via LiveCD.
It should be some problem with the USB booting routines, maybe due to a rather old machine :

http://www.asrock.com/mb/Intel/775Dual-915GL/