Vista - Weird Prob W/ Email Backup

Since April, when I got this machine, I've been backing up my Windows Mail
email every couple of days, in case I run into any "corrupted this or that"
problems. I keep the Windows Mail folder and the three registry entries in a
folder named by the date (i.e. mb 14 aug). I keep the backup from the
previous day, and the current day. I keep the 2 days folders in a main
folder in Documents called Windows Mail Backup.

Today, when I went to backup my email, 2 days of previously deleted folders
had reappeared. Those folders only had the Windows Mail folders in them.
The registry entries were gone. In addition, the current past 2 days folders
also only had the Windows Mail folders, and no registry entries. I know the
registry entries were there because I check the folder after I'm done with
the backup.

I checked the reliability monitor and I'm running at 10.0 so there hasn't
been any failures of any kind.

What happened? I appreciate any help anyone can give.