iPods, other FireWire/USB devices causing hangs at startup (#2)
iPods, other FireWire/USB devices causing hangs at startup (#2)
Various FireWire and USB devices can cause indefinite stalls in the Mac OS X startup routine when connected prior to or during the the boot process. In many cases the stalls can be obviated by simply not connecting such devices until startup is complete.
Identifying the offending device(s) is an exercise in trial and error; starting up with different sets of devices connected will typically reveal the culprit after a few attempts.
Stalls can also sometimes be alleviated if a device is disconnected. If you think a stall is occurring, try unplugging suspect devices and startup may proceed normally.
Among the most commonly implicated devices in this issue are FireWire and USB-based hard drives. As such, disk-based iPods -- with their wide usage -- have been particularly notorious in startup stalls. Specifically, some Intel-based Macs (the Mac Pro distinctly) seem to be more susceptible to startup stalls when disk-based iPods are connected. This could be a result of the differing FireWire and USB host controllers used in some models, or differing (Intel-native) kernel extensions used to communicate with the external devices.
MacFixIt reader Craig provides a case example:
"I just wanted to let you know that I'm also experiencing this problem with my 5G iPod (early model) connected to a 15" MacBook Pro Core 2 Duo 2.33 GHz. If the iPod is connected while the computer starts up, it hangs at the grey screen. Once I disconnect the iPod, the startup proceeds normally. I can report that this hangs occurs every time on 2 different MacBook Pro Core 2 Duo models I've tried. However, there's no problem when I connect the 5G iPod to my Mac mini."
Additionally, certain FireWire/USB controllers on the device end appear to be more prone to causing startup stalls. For instance, some users have reported repeated problems with drives that use Genesys controllers but an absence of such issues with drives that use Oxford controllers.
MacFixIt reader Tom writes:
"I just went through the full troubleshooting for an reproducible startup hang on an CoreDuo iMac 1st gen. In my case I was able to pin it down to one of my (multiple) external hard disks with an Genesys controller. If and only if the combo interface drive is a.) connected via Firewire at b.) an regular shutdown preceding an reboot or cold boot I get an startup hang after loading the KernelCache. None of the other (mostly Oxford 911 based, "no name") drives exhibit this behavior."
As previously reported, corrupt caches (particularly kernel extension caches) can sometimes be implicated in FireWire/USB device issues. Try the "deep" or "extended" routines offered by tools like Cocktail, Mac Pilot or Tiger Cache Cleaner before banishing a device from your setup.
Some other interesting reader reports on the subject:
MacFixIt reader Ryan writes:
"I always have a problem with my USB card reader. If it's plugged in it hangs."
Wally Grotophorst writes:
"I see the same behavior on an 6 week old MacBook Pro. I have an external OWC mercury drive attached via FireWire 400. Doesn't happen every time but often enough that I now make sure it's unplugged before I boot the MacBook, otherwise, about 80% of the time it will hang on the grey screen (prior to the darker grey Apple logo appearing) and never boot (even with multiple resets). Unplug the FireWire drive and it comes right up."
Another reader adds:
"I also have had the exact experience. Since the first day my MacPro hangs at the gray screen if my 5th Gen iPod is attached. I tried zapping PRAM, resetting the power management and disconnecting everything else (even the Apple Display). No matter which USB port it is plugged into, the iPod will cause a hang on 100% of warm restarts and most cold restarts."
Feedback? Late-breakers@macfixit.com.
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