Defragging OS X
When installing Boot Camp on my MacBook Pro, I received an error that files couldn’t be moved to create the Windows partition. Rather than take the Boot Camp Assistant’s advice and format the drive, I decided to enter the world of OS X Disk Defragmenting tools. I settled on iDefrag. The reviews were positive, and the bundled CD Maker app makes it a clear winner: you can build a bootable iDefrag CD that will be able to defrag your Mac’s boot drive.
After a successful defrag pass, I was able to partition my drive just fine.