Personalized Favorites Gone Strange

Does anyone know what happened and what I can do to fix it?

When selecting IE Tools > Internet Options > Advanced there is a checkbox under "Browsing" for activating personalized favorites. In the past, when checked, I have been able to click on Favorites drop-down menu and see only the favorites I have recently used. After a few seconds, the drop-down list would expand to show all the favorites.

For the past few days, however, something has gone weird and I see a partial list of favorites, some of which are sites I haven't visited for a long time. Some of the sites I visit almost daily are not among the partial list of favorites, and the list does not automatically expand after a few seconds. The only way I can get to a couple of my normally used favorites is to either uncheck the "personalized" checkbox and restart IE, or open favorites on the standard toolbar where the Gold Star is located.

I think I have inadvertently changed something and I can't discover what it is, or IE has become corrupted.

Anyone have an idea about what happened?