I have been having a persistent problem with date conflicts between the file dates(looking at file properties) and the pdf dates(looking at pdf metadata properties). When I import the create date and modification date via an import, the process is setting the file dates to "0". Once there is a mismatch between the pdf dates and the file dates, I get a File Not Found error and cannot update the files in any way.
I then have to have another application that sets the file dates from zero so they can be re-read. This is a giant pain and making pdf explorer not usable for importing metadata.