I suppose the screen you are talking about is Grub, but if it's not, correct me and please specify the screen you are talking about and give more details, a screenshot if possible would be great!
Considering the screen that you are calling 'Ubuntu / Advanced Settings...' is Grub:
The reason should be that your keyboard isn't turned on at this moment, if you can, change the USB, connecting your keyboard to another port. If it's not possible, maybe because your keyboard uses PS2 instead of USB or because you are on a laptop, so you will have to avoid this Advanced Settings screen, for that you could use Grub-Customizer to set a direct startup, without passing through Grub. Install Grub Customizer with these commands:
sudo add-apt-repository ppa:danielrichter2007/grub-customizer
sudo apt-get update
sudo apt-get install grub-customizer
Then you should predefine the option (kernel) to load and set time to 0 seconds and to start automatically from the first option.