Maybe try making sure you have disposed of your Excel object before attempting to open the CSV.
Or maybe sleep the VFP thread for a couple of seconds to give things a chance to flush.
declare integer sleep in "kernel32" long dwmilliseconds sleep(2000)
I assume you have Excel hidden during this. Maybe introduce a flag that will make it visible during this process when run onsite so you can see if it is calving at a particular point for the users.