Best option is to avoid it.
You can use a plug in to get a list of the files in a given directory.
If you put the directory inside your documents folder, you can use Get ( DocumentsPathListing ) to list the contents of that folder
And a system script could be used to list the contents of a folder in text file that can be imported to get the list of files in a given directory.
I now use the free Base Elements plugin, which works perfectly:
BE_FileExists ( "F:/database/scans/SCAN.pdf" )
Thanks again Phil!