Hi,
Update, the inability to add a New Source Folder problem was as the error indicated a "duplicate path exists". However, the problem is that the project built successfully (no errors) and the duplicate path existed in the setup for Path and Symbols/Includes. I do not know how the duplicate entry was creatded. In this case the error can be duplicated by explicitly specifying a path such as c:/CW10/workspace/myProject/Sources and ${ProjDirPath}/Sources. It does not matter if the duplicates are in the same languages folder or not, in my case they were not.
Regards,
Will