The addition for Manage Your OneCare Circle has been in the interface for some time and if you don't have more than one PC on your subscription or have no need to manage the Circle, ignore that link.
As for why your backup settings have been corrupted and OneCare itself crashes when you attempt to access them, I can't say. However, you can try the following.
1. The database reset tool -
http://www.microsoft.com/downloads/details.aspx?FamilyID=4bc2594b-95ab-4235-b5b8-41656b38480f&DisplayLang=en
2. If that doesn't solve it, consider reinstalling OneCare and activating the reinstall by signing in with the same LiveID that you initially subscribed with when you click on Subscribe. Note, open OneCare and click Help/About... before uninstalling to see the subscription ID.
3. Or, contact support for assistance.
How to reach support (FAQ) - http://forums.microsoft.com/WindowsOneCare/ShowPost.aspx?PostID=2421771&SiteID=2
-steve
