problem importing scanned files by vuescan

using nikon coolscanV film scanner, imac and lightroom4.  for the most part all is going well EXCEPT that when i try to import i get the following message on some files "Preview unavailable for this file".

there could be 10 files.  all have this message with the exception of 1 file.  that one file will be successfully imported.

have emailed ed hamrick but no answer so far.

anyone ever run up against this problem?