DVD-RW Disc Does not Show Updated Files

I use a DVD-RW to backup my data.
I recently bought a new Vista machine and am trying to make sure the data is
backed up and restored OK.
I use a program called "Backer" that detects changed files and copies only
the changed files.
It does not seem to work correctly under Vista.

So I updated a couple of files on the DVD-RW on another (XP) PC.
Reinserted the DVD-RW on the Vista PC and opened the file folder when
prompted.

Low and behold the Vista machine still shows the old dates for the updated
files !!!

I verified the DVD-RW was actually updated on 2 other PC's (one Vista and
one XP).

So, what does one need to do to get Vista to update the DVD file display (I
tried "Refresh")?

Thanks.