Q: "Do not enter" sign after iDefag finished

My wife's MacBook Pro (17") running 10.6.8 was sluggish so I ran iDefrag 2.1.1 successfully. It was still sluggish so I ran it again. (Both times restarting using the prompt in iDefrag.) The second time it successfully finished the defrag but when I restarted the MBP the Apple appeared at initial startup, the grey wheel spun for a bit and then another grey screen appeared with a grey "do not enter" symbol and the grey wheel spinning eternally. (The "do not enter" sign/symbol is a circle with the slash through it.)

I have booted her MBP as a target disk connected to my MBP (also a 17" running 10.6.8). I can see and access everything on her hard drive no problem. I tried rebooting my MBP using her MBP and I get the same "do not enter" sign.

So I ran Disk Utility from my MBP and it said "the volume appears to be OK."

So I bought and ran DiskWarrior 4.4 (I had DW 4.0 but it wouldn't run on 10.6.8). It says that the "drive is functioning normally".

I then used DW 4.4 to "Repair Disk Permissions" and "Check All Files & Folders" and it reported:

Open error 18446744073709551594: "unknown error: -22" on usr/libexec/postfix/error

Open error 18446744073709551594: "unknown error: -22" on usr/libexec/postfix/qmqpd

Open error 18446744073709551594: "unknown error: -22" on usr/libexec/postfix/trivial-rewrite

Open error 18446744073709551594: "unknown error: -22" on usr/libexec/postfix/virtual

...then a bunch of others with the same Open error number.

Then it said that a bunch of .plist (Epson, HP and others) cannot be repaired.

Then I rebuilt the directory and it said: "All file and folder data was easily located." "Comparison of the original and replacement directories indicates that there will be no changes to the number or contents of files and folders."

Still the same problem at startup... "do not enter".

So I restarted holding command-v to see what it had to say and it reported numberous things, such as:

Can't load kext com.apple.driver.ApplefileSystmeDriver - failed to resolve library dependencies.

kext com.apple.driver.AppleFileSystmeDriver failed to load

Kext com.apple.iokit.IOAHCIBlockStorage - library kext com.apple.IOKIT.IOStorageFamily not found.

kext com.apple.driver.AppleFileSystemDriver failed to load (error 0xdc00800e)

The other kext that failed to load with the same error are:

com.apple.iokit.IOSCSIMultimediaCommandsDevice

com.apple.iokit.SCSITaskUserClient

Then I get:

Couldn't alloc class "IOSCSIPeripheralDeviceType05"

Couldn't alloc class SCSITaskUserClientIniter"

The OS install disks that came with this MBP are 10.6.3 and when I tried to do a re-install it said that it couldn't install on this Mac. So I thought that I'd install Lion and see if that fixes things but I can't find it on the store (maybe because Mountain Lion comes out next month?)

Any suggestions?