Disk storage graphic and usage amount inconsistent?

I have a Macbook Air(6,2) with 120 GB SSD. When I checked About This Mac --> Storage, I see inconsistent information.

It says 87.89 GB free but Apps take up 92.65 GB. So there should only be about 30 GB free according to the graphic. However, I believe the graphic is wrong because OmniDiskSweeper says Macintosh HD is ~30GB.

Why do the graphic and numbers disagree?

Blame Spotlight. About this Mac relys on Spotlight's data, and it's clearly screwed up here. You can fix this by forcing Spotlight to reindex your hard drive. Goto System Preferences > Spotlight > Privacy tab. Then add Macintosh HD into the list, then remove it. Spotlight should start reindexing your hard drive. (You can test this by pressing CMD Space and entering an equation. It should say indexing).

(Oh, and this is a duplicate of this Finder and About this mac shows different free space sizes?)