[64 bit] Ubuntu Server 12.04 64bit won't boot without usb flash

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http://ubuntuforums.org – I installed Ubuntu Server 12.04 64bit from a usb flash drive that I setup with YUMI. I've reinstalled it twice. The 2nd time I manullay setup the partitions but it still won't boot without usb flash. I'm installing it on a dell gx620 2gb ram n 2tb hd. The bios is finicky but appears to be set right but when I boot without a flash I'm prompted "No boot device available - strike F1 to retry boot, F2 for setup utility. I've tried a few things from google searching including this but still no luck. Heres my fdisk -l: Code: Disk /dev/sda: 2000.4 GB, 2000397852160 bytes 255 heads (Hardware)