After upgrading from 10.7.1 to 10.7.2 with the hard drive encrypted with FileVault 2, the system would not boot (displayed a circle with a line through it). After searching I found a thread that seemed to point to PGP still having some parts left around, even though I wasn’t using PGP Whole Disk Encryption (WDE) anymore thanks to FileValut 2.
Unfortunately I could not seem to access to the files because a) the system would not boot and b) the system was encrypted with FileValut 2. Calling Apple didn’t yield a solution except re-formatting the machine and losing all data, but stumbled upon a way to not have to do that:
1. Restart the machine and hold Cmd+R to restart in Recovery Mode
2. Under the Apple menu (top-left) select ‘Startup Disk…’
3. Click on your encrypted disk, then click ‘Unlock…’ (mine is labelled ‘Macintosh HD’)
4. Enter the password of a user who can normally start up the machine and click ‘Unlock’
5. Hit Cmd+Q or go to Startup Disk menu and choose Quit Startup Disk
6. Under the Utilities menu, choose Terminal
7. Type cd /Volumes/Macintosh\ HD (enter the name of your drive instead of Macintosh HD) and hit enter
Voila, now you have access to all of your files on the encrypted drive!