On my MacBook Air, I'm trying to set up a dual-boot of Windows. I've done this in the past, and generally the process has been pretty straightforward. However, this time - that's not the case. When using the Boot Camp Assistant, I'm told that I need 28GB of free space. According to the drive icon on my desktop, my boot disk has nearly 60GB of free space. However, in About This Mac > Storage - I'm told that I only have 25GB of free space. I've already tried shrinking and expanding the drive in Disk Utility, as well as booting into single user mode and typing "/sbin/fsck -fy" and rebooting. None of this seems to work. What's the deal?