When I select Boot from hard disk from the USB stick boot menu, my system keeps booting to the USB stick. What’s wrong?

The short answer is that nothing is wrong. Some systems, when configured to boot from USB devices first will always reboot to the ArcaOS installation USB stickt, and not the hard disk, even when the hard disk has been selected from that menu. The good news is that the workaround is easy: simply remove the USB stick, allow the system to start booting from the hard disk, and reinsert the stick.

Alternatively, if your system provides a key to press to access a temporary boot device menu, press that, select the hard disk, and allow the system to boot normally.

More information is available on this wiki page.