unable to boot with all my drives plugged in - to / OR a live usb

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http://askubuntu.com – For a little over a year, my home server has been plugging away just fine. It had a 300GB IDE drive with ubuntu on it, and three 2TB drives on SATA ports in an mdadm RAID5 array. I lost a drive last week, and it was suggested to just try restarting it before doing anything else. Since doing that, however, I've been completely unable to boot into a working ubuntu system without unplugging ALL of the 2TB drives. I've identified the failed drive, as it doesn't get recognized in bios at all, but when I plug either of the other working drives in, I can't start at all - even with a working live (HowTos)