I was trying to create a RIA Services Class Library in VS2010 today and it kept failing to create both of the required projects with “A project with that name is already opened in the solution” as the error.
After searching around I’d found other projects that had a similar issue and the common thing was they were using AnkhSVN. There are 2 workarounds that also worked for me:
1. Disable AnkhSVN create the project, and re-enable it.
2. When you create the project make sure the casing exactly matches the actual directory e.g. use C:\Users\BronwenZ\Documents\Visual Studio 2010\Projects and not the default of c:\users\bronwenz\documents\visual studio 2010\projects