I am also having this problem. I can start Ubuntu if USB is disabled in bios but then the usb keyboard wont work in grub and I cant choose which O/S I want to use.
-- USB mouse causes the system to hang during boot https://launchpad.net/bugs/40015 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
