[ubuntu] Problem Getting To Login Screen

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http://ubuntuforums.org – hi, I have Ubuntu 12.04 on my desktop. a couple of times recently when I turned my computer on, instead of going to the Login Screen the computer stopped on a black screen saying something like - Lyn-desktop(I think)-Login_ I turned the computer off and restarted it and it went to the Login Screen. but that may not always work so I would like to know - what can I do if the computer stops on that black screen again to get me to the Login Screen? thanks lyn (Hardware)