I'm trying to boot into backtrack r2 from a usb on my acer aspire 1690 laptop running ubuntu, but when ever I try to a at first see a flash of a black screen with white text saying something like syslinux but then it just goes to a white screen that makes a beep every time i press a key. I tried remaking the usb and checking the md5 of the iso and everything is fine. Anyone know what could be going wrong?