Bootable support failed during boot

Hello,

I just installed Acronis True Image 2014 Premium - build 6614 - and try creating a bootable support on USB memory stick.

This process is working well, but after reboot, the system display "demarrage du chargeur Acronis" then "Acronis Loader : erreur fatale : Disque (partition) de demarrage non trouve." and stops.

The operating system is XP SP 2. It is not a brand manufacture computer.

What can you suggest ?

Thanks in advance

Regards