USB keyboard doesn't work in boot menus
Interestingly, my USB keyboard works both in BIOS and in fully booted operating systems - but it doesn't work in the boot menus, for example in Grub or in the boot menu of several linux live CDs. PS/2 always works. Because there is no mouse detection in boot menus, I haven't had the chance to try it out with other USB devices. What could be the reason for that?