Hi Jim,
I tried this a few times in LabVIEW 6.0 but the Move VI always seemed to work correctly. I have checked through some internal databases and I didn't find any reports of an error with the Move VI. However, since this is such an old version of LabVIEW, it's possible that any error reports might already have been archived.
About what percentage of the time does the file get copied and not moved? Have you replicated this with a very small VI that you could post here?
Thanks,
Megan B.
National Instruments