After System Update last night, the system will not boot with IOPlatformExpert.cpp:1504 error 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 Options when booting up, and was able to boot to Windows 7 (bootcamp)... and was able to boot to the "Recovery", which let me choose


Restore from Time Machine Backup
Reinstall Mac OS X
Get Help Online 
Disk Utility


what should I do now to fix it so that it can boot again?
Tried clearing your PRAM? Hold down Option + Command + P + R before turning the mac on, keep holding them until the mac makes the startup chime again (twice in total).
Apart from that, boot off the recovery partition and reinstall over the top of your hdd. Your data won't be changed, the OS will just be repaired.