It appears we have been working with Microsoft on this one. It seems like a difficult issue to reproduce and fix since we are not seeing it occur very often in large environments. I have this suggestion as a workaround to try:
1) upgrade to any newer PGP version first - 10.2 MP5 or newer
2) run a pgpwde --sync-bgfs and then try again:
pgpwde --sync-bgfs --disk 0 (or replace disk 0 with the drive number in question)