Francisco Fernandez do you have other USB devices working in Grub? If not, you may need to try modifying your handoff settings in the BIOS. If that allows you to function in Grub but takes some other function away, it may be necessary to switch the setting back and reinstall the OS or recompile Grub or something, especially if settings were changed after the initial OS installation. Depending on your motherboard, it may even be possible that some USB ports behave differently than others, so it could also be worth exploring that possibility first. All of this is conjecture on my part, though, so I probably can't really help beyond these initial suggestions.