I have had Lion for a 2, 3 months on the iMac 27 inch purchased last October (2011). Last night I chose to update the system, and deselected iMoves update because it was 1GB, and chose only 4 updates, including iTunes, Safari (i think)... But the update says error, and ask to restart the system (it won't restart itself, so I waited 30 minutes, and then pressed the Power button for 10 seconds, to let it power down, and press Power again to power it up). However, after that, the system failed to boot up, showing a panic(cpu 0 caller .....)" "Unable to finder driver for this platform: \"ACPI\". ... xnu-1699.26.8/iokit/Kernel/IOPlatformExpert.cpp:1504 This is not typical of the upgrade process. So I searched the Internet for `IOPlatformExpert.cpp:1504` and some people said it is a hard drive error, but then I powered down and pressed the Options key when booting up, and was able to boot to Windows 7 (bootcamp)... and was able to boot to the "Recovery", which let me choose 1. Restore from Back up 2. Reinstall Lion 3. .... 4. .... what should I do now to fix it so that it can boot again?