it's so weired that i have to plug/unplug in my usb devices every time booting ubuntu. it happens for both installing ubuntu and booting ubuntu (10.10 and 11.10) the scenario is like: 1.bios checking - 2.grub start - 3.keyboard & mouse led OFF (black screen with a cursor on top-left) - 4.i plug/unplug in any usb devices - 5.everything is back to normal and ubuntu started it's really frustrating :( please advise the solution.