Lion hangs on shutdown "unmount of /net failed (45)"

Question

Hi,
my Lion MacBookPro hangs 95% of the times when shutting down with the messages
com.apple.launchd 1 com.apple.launchd 1 System: Stray process at shutdown: PID 296
com.apple.launchd 1 com.apple.launchd 1 System: Sending SIGTERM to PID 396 and continuing.....
syncind disks... Killing all processes
continuing
unmount of /home failed (45)
unmount of /net failed (45)
Any help with that? I suspect Parallels having to do with that. It just stops there and stays there for hours......
Some more console log messages (higher above) are
/prl_hid/ Parallels HID Helper stopped.
Kext unloading is disabled (com.parallels.kext.prl_hid_hook)
Kext unloading is disabled (com.parallels.kext.prl_hid_hook)
Can't remove kext com.parallels.kext.prl_hyervisor; services failed to terminate - 0xdc008818
Any help appreciated......
GeniusBar Guys couldn't help.
Best regards,
Peter

Answer 1

Dear DS Store,
Thanks for the response.  (Is this what you mean in your step by step tutorial by giving credit?)
I should also preface my run-through of your tips by noting that my wife's Macbook air will shut down properly and get past the "unmount of /net failure" business without problems if I do not run iTunes (current version 10.6.1).  I can run Microsoft Office, Chrome, Mail etc no problem without triggering this problem.  In these circumstances I've been able to see that the next messages that SHOULD show up after the "unmount of /net failed (45)" are:
done
MACH Reboot
wlEvent EN0 EN0 Link DOWN
(These lines blink by so quickly that I couldn't read them, I had to freeze frame a video I made of a proper shutdown sequence).
However, when I run iTunes, I ALWAYS get this failure where it freezes after the "unmount of /net failure (45) line" and is never able to shut down properly. 
This problem occurs with both local accounts as well as with mobile users syncing to my portable home directory server.  (Even with a local account with nothing in the iTunes library).
I should also note that before I got your response to my question, I had already undertaken to reinstall OS X (with full software update done immediately after), and still was encountering the same problems after.
Regarding your steps:
Step #1 SMC reset - Done, did not change outcome - still hung at shutdown
Step #2 PRAM reset - Done, still hangs at shutdown
Step #3 Startup manager - not done as I have no problem with getting into the boot volume
Step #4 - Repair disk - DIsk repaired using Lion recovery HD, no errors found, did not change outcome
Step #5 - reset home directory permissions and ACLs - done for all local accounts, portable home directory accounts, root - still hanging at precisely the same point
Step #6 - hardware test not done, problem seems to be software/OS related.  (going to run extended tests overnight)
Step #7,8 - did not seem pertinent to this situation, as it is possible to boot into all accounts no problem.
Step #9 - all data backed up on Time Machine, and also synced to server
Step #10 - software updated done
Step #11 - permissions repaired - still problematic
Step #12 - Onyx cache cleaning - plists check out fine, cleaned out all caches (except system logs), did all the maintenance tabs (did pretty well everything I could see as options) - problem still persists.  (I had hoped that cleaning kernel and dyld caches might do the trick, but no).
Step #13 - Deleted ~/Library/Preferences/com.apple.iTunes.whatever and anything.plist (3 files altogether) - same problem.  (There did not appear to be any other corrupt plists that needed deletion)
Step #14 - Activity monitor - no runaway processes.  mdworker busy, but due to spotlight caches being purged in step 12. System Diagnostic log shows nothing. 
Step #15 - there isn't any third party software on my wife's macbook air that isn't running on my own macbook air and macbook pro (both of which are not facing this problem).  I tried to uninstall and reinstall iTunes prior to getting your advice (this is a PITA, by the way!!!!), and had ended up with 10.6.0 installed (since the downloadable installer from Apple at the moment isn't the latest 10.6.1 version), and software update not recognizing the need to update, which is when I went ahead and reinstalled OSX. This did not clear the problem.
Step #16 - created a brand spanking new account called test.  Problem continues to occur with the new account.
At this moment am wanting some feedback on what you think sofar of the problem before I go ahead and do something more destructive or tedious.
I should note that I do not seem to be able to find any reference to the problem in the system.log or kernel.log files in Console.  When I look through kernel.log there is nothing logged around the time the failure to shut down occurs, and in system.log, the last logged item is usually 1-2 seconds before I get the stream of other stuff that occurs as shown in the screenshot above, which includes a statement to the effect of "Userspace shutdown finished at [timestamp here]" etc etc....  I do not know if this other stuff is logged elsewhere, or not at all, as I have never seen this stuff in the logs in console.
Thanks in advance.
Peter T