MacBook Pro5,3 (mid '09), with 1TB 7200 HD, OS 10.10.2 at first had an unresponsive display upon opening lid / waking. Only holding power down for 10sec to reboot snapped it out. Day later it started going into a constant reboot cycle, either with a 6-language message on a gray screen, or simply a Mac boot chord, followed by black apple on gray screen, and a progress bar that seems to only get to a third, before kernel panic occurs. It just reboots itself. Every 10th or so cycle, the OS actually boots up. It has booted in Safe Boot more frequently. Reinstalled OS. Same problem. Ran Geekbench - awful results on read / write, and other HD related functions. Graphics and memory - average. After frequently getting to Safe Boot, decided to zero-write and clean install. Same problem. Problem seems to be tied in with "sleep" function. No Mac repair person has been able to isolate the issue, they are all puzzled and just say "get logic board replaced". In verbose mode, it most often hangs during the "fsck_hfs" or just after "Previous Shutdown Cause: 3", "DSMOS has arrived" and "Sandbox: denying permissions, but not always, it's a different line almost every time. It says "removed 5 orphaned files", but sometimes 4 or 1 file.

Thermal Sensor? Fans do blast like crazy. Makes no sense to do a costly Logic Board swap on a 6 year old machine, does it?


  • Please check your Console for I/O errors, there should be none.
    – Ruskes
    May 26, 2015 at 7:26
  • The verbose replies you allude to are perfectly normal log replies during the boot process.
    – njboot
    May 26, 2015 at 9:10

2 Answers 2


If it most often hangs during fsck then I would lean pretty hard towards it being a drive failure. Also, resetting the PMU could be worth a shot. Does the battery hold a charge?

If so, shut down, unplug from charger, wait 5 minutes, seriously wait 5 minutes, then boot from the battery. shut down after boot, reconnect your power adapter. Boot. Notice I wrote shut down specifically and not re-boot. Give that a try.

As far as the fans going full blast- this is normal for safe mode boot.


The shutdown cause 3 is a hard shutdown, although the shutdown cause -3 is usually associated with the thermal sensor. If you've negative 3, then you're advised to run Apple Service Diagnostics to check which sensor went beyond expected thermal limits.

Otherwise if it's 3, then you should look for the reason somewhere else. In general positive codes relates due to software, and a negative relates to a hardware issues.

See: Are OS X shutdown cause and sleep cause numbers listed/explained anywhere?

If you've checked already your HD for any errors and fixed them, you should also try the followings:

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