Find My Mac in Mountain Lion System Preferences says "Recovery partition required"

Last week I noticed Find My Mac no longer works.

In System Preferences > iCloud > Find My Mac is grayed out and underneath it reads, "Recovery partition required."

Selecing more, brings up this message:

My hard drive was never partitioned and Find My Mac worked fine until recently.

Searching for this problem brought up an Apple help page. I followed the instructios, got no errors in the Disk Utilities. I downloaded the Recovery Update, but when I went to run it, the installer said I needed 10.7. I'm running 10.8.3.

Any idea how I can get Find My Mac to work again? Thanks!