Apple has released a "supplemental update" to OS X version 10.6.7 specifically for the 13" MacBook Air model released late last year. The update reportedly fixes an issue that made the devices "unresponsive when using iTunes," and it clocks in at a tiny 461 KB.
As always, the updates are available via Software Update, so if you've got a newish MacBook Air, load up the app and check to see if you need to install it. Afterwards, you'll be able to use iTunes without issue among other fixes.
Apple OS X Yosemite