It sounds like your repair isn't working properly because it is not configured properly. The message "The name has already been shared" seems to be the key indicator of this. Either there is a configuration piece that you are not setting up properly or it wasn't configured properly during the first installation. This MSDN page seems to have some answers:
http://social.msdn.microsoft.com/Forums/fa-IR/sqlexpress/thread/90c61aef-f8e1-45ab-a37c-b1ce3ec67e03[
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My suggestion would be to first assess if you really have a problem. Use the PortQuery or PortQueryUI tool to figure out if the correct ports are open on your machine. Here is a link to that tool:
http://www.microsoft.com/en-us/download/details.aspx?id=24009[
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Next, if you are sure there is a problem, I would recommend completely uninstalling SQL server and then reinstalling it after a reboot. Maybe something got corrupted during the installation. A complete redo should fix the issue. Don't forget, though, that you will need to adjust your firewall and configure SQL before you will be able to access it remotely.