I had this problem before, but did not take notice of it then, but when i wanted to restore the backup whit the smaller file size all went wrong by restoring the database and the restore stopped whit an error telling me it could not find the database in the archive leaving me whit a mess. I had to restore an older backup using kickstart.php which give me lots of extra work to restore the latest articles.
Now on 27 September 2010 al of a sudden it started again, all backups are a lot smaller in size (no errors where reported), it doesn't matter if i use Akeeba Backup Pro from the back-end, using lazy backup or Akeeba Remote Control. I do not understand what's causing this, nothing special happened nothing was changed or installed that could interfere whit the backup process it just happened.
Can you help me out, i cant find out what causes it. I attached the latest log file, hope it's of any use to you.
grtz, Z. :(