When you say "compiled" I assume you mean that you turned it into an executable. You can debug your built executable with LabVIEW 8. To do this follow the instructions in the help article (Help>>Search the LabVIEW Help) titled Debugging Applications and Shared Libraries.
From the sounds of it, I'm betting you have a race condition. What happens if you don't use local \ global variables? Let us know what you find.