lfs gets random error, "cannot obtain information from file"

Seemingly randomly, folders suddenly become inaccessible to lsf in the Corona Simulator.

This code usually works, but occasionally it stops reports it can’t read a particular folder, with the “reason” being “cannot obtain information from file”.

for myFile in lfs.dir(doc\_path) do local attr, reason = lfs.attributes (myFile) end

Help?