Server asks for username and password on boot

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http://askubuntu.com – I installed the Ubuntu server 12.04 easily, however, when I boot it asks for a username and password. I don't know my previous username or password from Windows XP. I am currently trying to install any version of Ubuntu I have in my arsenal to recover the PC, but all intents so far have failed. They worked on other computers but not on this one, the error I get is No DEFAULT or UI configuration directive found! I have tried all the solutions found on this site but to no avail. I don't have a Windows Ultimate boot disk and I'm out of CDs to burn. I can, however, make live USBs. Any Sugges (HowTos)