I'm running a MacBook Air Nov. 2010 model with a 128 GB flash.
Presently my drive totals 68 GB. But there's only 13 GB free, immediately after a reboot.
I've shown every invisible file, folder, etc (including all UNIX directories) and calculated all folders, and all the folders add up to 68 GB.
Where is the missing 40 GB?
I've also used GrandPerspective and DiskInventory X and everything shows up as expected.
I recently re-formatted and reinstalled the Mac from scratch, including all apps. System should be totally clean.
Would WhatSizeMac show it? I don't want to spend $13 on the software if it's not guaranteed to show it.