broot - 2012-03-26

I ran dban last night and went to install ubuntu from a liveusb formatted in unetbootin. No matter how much I try and make my computer boot from the usb it comes up as "boot error" or "no bootable device - insert boot disk and press enter". I have an acer aspire 5315. I've tried to disable booting from hard drive as was suggested in a few places on the forum but the aspire BIOS doesn't seem to let me disable anything in boot, just rearrange the order. Any help would be greatly appreciated.