Stu Farnham wrote:
I can boot and log in, both from the user and the admin accounts, but nothing works -- no finder, terminal, etc. -- even in safe mode.
Sounds like the issue is then confined to both users when it installed and you can't use either user to create a new account as both are hosed by Crystal.
What you do have is:
1: Lion Recovery Partition
2: Single User Mode
What I would do is hold command r keys and boot into Lion Recovery, use Disk Utility to format a new blank powered external drive 1 partition, Option: GUID, Format: OS X Extended (journaled) then quit and install Lion onto the external drive. You will need your AppleID and password to get Lion again.
Reboot holding the option key down and you should be able to boot off the external Lion drive, then grab your user file folders from both users.
Another method is to use Firewire Target Disk Mode (hold T and boot problem Mac) connect a Firewire cable (800 to 400 adapter if needed) to another Mac and boot that one, the hard drive appears on the desktop to grab files.
None of the above steps are required if you have a recent copy of the files off the machine already on a regular storage drive.
(don't include TimeMachine as that also might be hosed)
Once you grabbed files off you can try this method here that worked on 10.6 to create another user while in Single User Mode (hold command s while booting)
http://osxdaily.com/2010/08/10/forgot-mac-password-how-to-reset-mac-password/
Because the Crystal installer should have installed for all users, your not running the installer now, so the new user should be untouched.
From this new Admin user account you can transfer your files via the Root Level>Shared folder, create another users etc. Even attempt to manually uninstall the crap by Crystal in the other infected users if possible.
If Crystal installed something in OS X itself (not a kext file that safe boot could disable) then a command r boot into Lion Recovery and doing a simple install of OS X (no Disk Utility Erase!) should boot it out of OS X, but then your users could remain screwed up still, only trying and finding out will see if this alone is enough.
If both OS X and your users are screwed up, then only a total erase (DIsk Utility) of the OS X Lion Partition from the Lion Recovery Partition, followed by Lion install, all your programs again (iLife from AppStore) and setup two new users, and return files from the external drive will suffice.
Keep in mind that each user, the applications folder and OS X are essentially seperate.
https://discussions.apple.com/thread/3358920