Typically, this occurs when vi's have duplicate names. Find all instances of Snd Gen...vi and rename the dupes.
See the handy dandy ni doc strangely titled "What Do I Do When I am Building An Application and I Get Error 1: "Error saving file xxx.vi"?" at:
http://digital.ni.com/public.nsf/3efedde4322fef19862567740067f3cc/283d12080ec1d339862568d2005617b0?OpenDocument
or the Application Builder Troubleshooter at:
http://www.ni.com/support/labview/toolkits/appbuild/
2006 Ultimate LabVIEW G-eek.