As Golem reports, there’s a problem with Microsoft’s OneCare that can lead into the deleting of the entire PST file (which contains all your e-mails). Well, that’s definitely a great protection against e-mail viruses, but perhaps not what you want… 😉
As always, doing a backup is a great idea if you like your data.
You can backup or synchronize your Outlook data with Easy2Sync for Outlook. However, if you only want to automate the backup your PST-file, simply use Easy2Sync for Files. Even the Freeware Edition will be good enough for this job. You can get it here: Download Easy2Sync for Files.