Haven't seen this before, and doesn't occur on my own blogs.
I've tried deactivating several plugins that I thought I had installed on a client's site, but to no avail, I'm not getting an options/manage page for the backup plugin, thus no backups are being sent via cron, nor can I manually backup the database via the plugin.
(Please save the lectures on other ways of doing this, etc. It's not just my personal choice, many people prefer the no-brainer plugin option. Obviously someone thought enough of it to package it as a default plugin...)