Mac boots fine normally, except when in safe mode.

Holding down shift when booting gets me to the progress bar on the grey screen. Progress bar gets about half way before mac reboots.

I modified nvram boot-args to get a better look:

sudo nvram boot-args="-x -v"

It definitely gets through fsck, skips loading kernel extensions (since it's in safe mode), does something with the network interfaces, then this is the last thing it wips through...

Aug 22 11:56:21 Crockpot com.apple.SecurityServer[15]: Succeeded authorizing right 'com.apple.ServiceManagement.daemons.modify' by client '/usr/libexec/UserEventAgent' [10] for authorization created by '/usr/libexec/UserEventAgent' [10] (100012,0)
Aug 22 11:56:22 Crockpot fseventsd[37]: event logs in /.fseventsd out of sync with volume.  destroying old logs. (1 174 330)
Aug 22 11:56:22 Crockpot fseventsd[37]: log dir: /.fseventsd getting new uuid: 5C379650-26FA-428F-B81F-4FE4349D50B3
Aug 22 11:56:23 Crockpot mDNSResponder[39]: mDNSResponder mDNSResponder-379.27 (Jun 20 2012 15:40:55) starting OSXVers 12
Aug 22 11:56:23 Crockpot systemkeychain[35]: done file: /var/run/systemkeychaincheck.done
Aug 22 11:56:23 Crockpot configd[17]: network changed: DNS*
Aug 22 11:56:24 --- last message repeated 1 time ---
Aug 22 11:56:24 Crockpot mDNSResponder[39]: D2D_IPC: Loaded
Aug 22 11:56:24 Crockpot mDNSResponder[39]: D2DInitialize succeeded
Aug 22 11:56:24 Crockpot mDNSResponder[39]: Adding registration domain 273025955.members.btmm.icloud.com.
Aug 22 11:56:24 Crockpot kernel[0]: MacAuthEvent en1   Auth result for: 00:23:69:35:dc:fe  MAC AUTH succeeded
Aug 22 11:56:24 Crockpot kernel[0]: MacAuthEvent en1   Auth result for: 00:23:69:35:dc:fe Unsolicited  Auth
Aug 22 11:56:24 Crockpot kernel[0]: wlEvent: en1 en1 Link UP virtIf = 0
Aug 22 11:56:24 Crockpot kernel[0]: AirPort: Link Up on en1
Aug 22 11:56:24 Crockpot kernel[0]: en1: BSSID changed to 00:23:69:35:dc:fe
Aug 22 11:56:24 Crockpot kernel[0]: en1::IO80211Interface::postMessage bssid changed
Aug 22 11:56:24 Crockpot kernel[0]: AirPort: RSN handshake complete on en1
Aug 22 11:56:25 Crockpot cfprefsd[19]: CFPreferences failed to read preferences data. Errno was 21
Aug 22 11:56:25 --- last message repeated 1 time ---
Aug 22 11:56:25 Crockpot airportd[30]: _doAutoJoin: Already associated to “burnum”. Bailing on auto-join.
Aug 22 11:56:25 Crockpot com.apple.kextd[11]: Can't load IOBluetoothSerialManager.kext - ineligible during safe boot.
Aug 22 11:56:25 Crockpot com.apple.kextd[11]: Load com.apple.iokit.IOBluetoothSerialManager failed; removing personalities from kernel.
Aug 22 11:56:25 Crockpot cfprefsd[19]: CFPreferences: error renaming file blued.plist.HXuEmQn to blued.plist.
Aug 22 11:56:27 Crockpot awacsd[52]: Starting awacsd connectivity-77 (Jun 20 2012 15:40:49)
Aug 22 11:56:27 Crockpot com.apple.SecurityServer[15]: Succeeded authorizing right 'system.services.systemconfiguration.network' by client '/System/Library/Frameworks/SystemConfiguration.framework/Versions/A/Resources/SCHelper' [54] for authorization created by '/usr/sbin/awacsd' [52] (100003,0)
Aug 22 11:56:27 --- last message repeated 1 time ---
Aug 22 11:56:27 Crockpot awacsd[52]: Configuring lazy AWACS client: 273025955.p04.members.btmm.icloud.com.
Aug 22 11:56:28 Crockpot apsd[55]: CGSLookupServerRootPort: Failed to look up the port for "com.apple.windowserver.active" (1102)
Aug 22 11:56:32 --- last message repeated 1 time ---
Aug 22 11:56:32 Crockpot awacsd[52]: KV HTTP 0
Aug 22 11:56:38 --- last message repeated 1 time ---
Aug 22 11:56:38 Crockpot apsd[55]: CGSLookupServerRootPort: Failed to look up the port for "com.apple.windowserver.active" (1102)
Aug 22 11:56:47 Crockpot awacsd[52]: KV HTTP 0
Aug 22 11:56:49 Crockpot configd[17]: subnet_route: write routing socket failed, Network is unreachable
Aug 22 11:56:51 Crockpot configd[17]: network changed: v4(en1+:169.254.80.161) DNS* Proxy+ SMB
Aug 22 11:56:51 Crockpot UserEventAgent[10]: Captive: en1: Not probing 'burnum' (protected network)
Aug 22 11:56:51 Crockpot configd[17]: network changed: v4(en1:169.254.80.161) DNS Proxy SMB
Aug 22 11:57:07 Crockpot awacsd[52]: KV HTTP 0
Aug 22 11:57:23 Crockpot fseventsd[37]: Logging disabled completely for device:1: /Volumes/Recovery HD
Aug 22 11:57:25 Crockpot kernel[0]: Kext loading now disabled.
Aug 22 11:57:25 Crockpot kernel[0]: Kext unloading now disabled.
Aug 22 11:57:25 Crockpot mDNSResponder[39]: mDNSResponder mDNSResponder-379.27 (Jun 20 2012 15:40:55) stopping
Aug 22 11:57:25 Crockpot com.apple.SecurityServer[15]: Killing auth hosts
Aug 22 11:57:25 Crockpot UserEventAgent[10]: dnssd_clientstub DNSServiceProcessResult called with DNSServiceRef with no ProcessReply function
Aug 22 11:57:25 Crockpot configd[17]: dnssd_clientstub read_all(26) failed 0/28 0 
Aug 22 11:57:25 Crockpot configd[17]: [0x7fb025119ff0] SCNetworkReachability _llq_callback w/error=-65563
Aug 22 11:57:25 Crockpot UserEventAgent[10]: dnssd_clientstub DNSServiceProcessResult called with DNSServiceRef with no ProcessReply function
Aug 22 11:57:25 Crockpot mDNSResponder[39]: D2D_IPC: Terminated
Aug 22 11:57:25 Crockpot mDNSResponder[39]: D2DTerminate succeeded
Aug 22 11:57:25 Crockpot awacsd[52]: dnssd_clientstub read_all(4) failed 0/28 0 
Aug 22 11:57:25 Crockpot UserEventAgent[10]: dnssd_clientstub DNSServiceProcessResult called with DNSServiceRef with no ProcessReply function
Aug 22 11:57:25 --- last message repeated 2 times ---
Aug 22 11:57:25 Crockpot apsd[55]: dnssd_clientstub read_all(4) failed 0/28 0 
Aug 22 11:57:25 Crockpot configd[17]: SCNC: stop, triggered by configd, type PPPSerial, reason Terminated All
Aug 22 11:57:25 Crockpot configd[17]: _d2dCallback: D2D connection to mDNSResponder lost
Aug 22 11:57:25 Crockpot UserEventAgent[10]: dnssd_clientstub DNSServiceProcessResult called with DNSServiceRef with no ProcessReply function
Aug 22 11:57:25 --- last message repeated 4 times ---
Aug 22 11:57:25 Crockpot kernel[0]: Kext autounloading now disabled.
Aug 22 11:57:25 Crockpot kernel[0]: Kernel requests now disabled.

... before rebooting in the middle of the safe mode startup sequence.

Aug 22 12:01:10 localhost bootlog[0]: BOOT_TIME 1345662070 0
Aug 22 12:01:32 localhost kernel[0]: PMAP: PCID enabled
Aug 22 12:01:32 localhost kernel[0]: Darwin Kernel Version 12.0.0: Sun Jun 24 23:00:16 PDT 2012; root:xnu-2050.7.9~1/RELEASE_X86_64

Any ideas what's causing the safe mode boot to fail?

System Info

• MacBook Pro 8,2
• 2.2 Ghz Core i7
• 4 GM Ram
• Mountain Lion 10.8
• 500GB TOSHIBA MK5065GSXF Serial-ATA rotational disk