The project file looks valid and seems to work fine under visual studio but I get this error trying to upgrade using the version utility:

12:57:38: Running User Interface Version 11.2.20112.1000

12:57:38: Gathering volume and assembly information.

12:57:55: Analyzing Tracker.NET.csproj...

12:57:55: The project has references that need to be updated.

12:57:56: Could not load the project. Please see the Log file for more details.

12:57:56: Root element is missing.

12:57:56:    at System.Xml.XmlTextReaderImpl.Throw(Exception e)

   at System.Xml.XmlTextReaderImpl.ParseDocumentContent()

   at System.Xml.XmlLoader.Load(XmlDocument doc, XmlReader reader, Boolean preserveWhitespace)

   at System.Xml.XmlDocument.Load(XmlReader reader)

   at System.Xml.XmlDocument.Load(TextReader txtReader)

   at Infragistics.VersionUtilitySupport.Core.File.Types.DataSourceFile..ctor(String path, FileBase owner)

   at Infragistics.VersionUtilitySupport.Core.File.Types.AdditionalFiles.AddFile(String fileName, Boolean includeCodeBehindFiles, Boolean isWindowsPhone, List`1 listOfAssemblies)

   at Infragistics.VersionUtilitySupport.Core.File.Types.ProjectFile.CheckProjectForAdditionalFiles(Boolean isSLProject, Boolean isWP7, XmlNode node)

   at Infragistics.VersionUtilitySupport.Core.File.Types.ProjectFile.Analyze()