Claudine,
1. What happens when you use Explorer or some file manager - can you find your file that way (manually searching)? - Perhaps you have an erroneous path listed somewhere.
2. If you do find your file manually, can you open/launch your program by opening it from there?
3. Finally, perhaps you don't have ".vi" associated with your application (LabVIEW). You may need to check that.
These are just ideas to think about, because its unclear what your exact cause is - Good luck, Doug