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macrumors 65816
Original poster
Feb 15, 2002
I am experiencing a hang on OS X startup that has begun recently when rebooting. According to the system log, the hang is occurring at the line: Created prelinked kernel /System/Library/Caches/ .

Prior to that line, I have the following messages:

(Message shown 7 times)
/System/Library/Frameworks/CoreServices.framework/Frameworks/Metadata.framework/Versions/A/Support/mdworker MDS Error: unable to create user DBs in /var/folders/zz/zzzivhrRnAmviuee++++KE+++3Y/-Caches-//mds

(Parallels software, message shown 2 times) prl_usb_connect.kext is not valid.

The hang can last ten minutes, forty minutes, an hour, or never recover. After the gray screen clears, the hard disk begins clicking rapidly, as if loading something, but then it goes quiet and the startup process hangs. The computer services are running in the background, as I can hear the hard disk clicking occasionally, and the screen blanks as if the Energy Saver functions are active. Sometimes the keyboard backlight comes on, sometimes not; sometimes the mouse cursor appears, sometimes not. One time I left the computer running overnight, and hours later I found it stuck halfway between the wallpaper appearing and the login window appearing, the screen showing an opaque gray over the wallpaper but no login window.

I have tried to delete the files in the folder and let OS X recreate them, but that didn't fix the problem.

I'm guessing that there's something wrong between the prl_usb_connect.kext and the creation of the kernelcache_i386... file.

In /System/Library/Extensions , there is something suspicious. There is one file that's not a file, but a Shortcut, and that's associated with prl_usb_connect.kext . The Shortcut points to /Library/Parallels/Parallels . Neither the Shortcut nor the .kext file appears to have been altered recently.

Should I delete prl_usb_connect.kext, delete the Shortcut to prl_usb_connect.kext, delete the files, and try again to let OS X recreate the files?

Should I clear the files in /var/folders/zz , including the folder zzzivhrRnAmviuee++++KE+++3Y that is mentioned in the logs?

What may have caused the problem to occur?


Staff member
Jan 23, 2005
Try holding the shift key at boot to start in safe mode. That will stop Parallels and any other third party apps from launching. If that fixes it, then you know it is one of the third party login/startup items causing this.

That drive clicking noise does sound a bit like you may have a failing drive there.
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macrumors 65816
Original poster
Feb 15, 2002
Regular hard disks always make clicking noises. That's not the problem. The problem is when the clicking noises stop, which means that the operating system has stopped.

The Safe Mode cleared the stall, as does Verbose Mode, but the stalling occurrence and duration is inconsistent.

Now it's getting worse. I just tried to launch the Dropbox application, and OS X froze. Not really, because only the screen froze, but the copy operation that I had running completed normally, and, according to the system logs, the system appeared to continue running until I killed it again. Dropbox never opened, and a line was left in the system log that doesn't appear to have a specific meaning: npvhash=4095

An Apple-associated application named ColorWhirled is also failing to start, and QuickTime is refusing to function after I had to kill the system because of yet another Black Screen lockout as the QuickTime window resized.

I suspect Parallels has somehow become a problem, but I can't kill that yet because I need it.

An underlying problem that I am finally beginning to recognize is the Black Screen graphics failure as is described here:

When this happens, the system really stops working. What's odd is that the Black Screen only happens when the system is doing the least amount of work in Apple applications (iMovie adding a title overlay in a video, QuickTime window resizing), not when actually watching HD video in iTunes or iMovie. If the hardware were bad as was the subject of the recall, why can it handle the hard loads that are pushing both the CPU and GPU to maximum?

When the screen freeze happens, the operating system continues running, including the screen saver, but no Sleep Mode happens (power down) even though the system logs indicate that the Sleep Mode activated. This stalling is the same problem that I'm experiencing on startup. I can hear the disk running something, then it stops and stalls for five minutes or more and sounds like a normal idle, and then the login window appears. It's the same behavior that I see when an application doesn't close or open correctly, and the screen freezes. The screen will blank out on its screen saver timer, active tasks will finish, but the screen freezes except for the mouse cursor.

I'm past my understanding of OS X at this point. What I know is that none of this was happening during the warranty period, and now the problems have turned into a serious headache.
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