Installing SQL Server 2012 on a machine that already had Visual Studio 2010 installed. During installation, a pop-up requested insertion of the Visual Studio DVD. It read the disk for a while, and then Setup failed with a message indicating that a certain file (related to SQL Server) could not be found in the disk. Of course it couldn't be found, at that time the disk on the drive was the one for Visual Studio; the setup process never provided the opportunity to insert back the SQL Server disk.
[Edit: As requested by the SQL Server Team, I have attached the Setup Logs (104 MB). Visibility of the file is set to "Microsoft Only"]