Bus errors and/or freezing upon restart after installing the Apple Displays software version 1.7 are caused by corrupted PRAM. Resetting PRAM by holding down the Command-Option-P-R keys at restart until the computer chimes twice, appears to resolve the issue.
Apple Displays software version1.7.1 is available for download from the Apple Software Updates web site at http://www.apple.com/swupdates.