Problem with finalizing DVD disks

Hello all,

I have a persistent problem while finalizing the DVD-R/DVD+R disks. When I finalize when the DVD disk space remaining is in the order of .5 GB or so, after finalizing I am able to view all the files on the disk(via Windows explorer). But when we attempted finalize, when freespace left is 40.96(20000 blocks) MB for DVD-R and 10.48 MB(5120 blocks) for DVD+R, the explorer shows only the first session. Can any body please give us a clue as to when it is safe to finalize(the probable freespace that would be needed considering the file size that need to be burnt) without loosing any data.

Best Regards,