Q: El Capitan installs & boots OK, but crashes on restart
The El Capitan installation went fine, it booted the first time without any problems, then it crashes after a restart. Often (but not always) I see "PCI configuration begin/end" messages. Then it automatically reboots, so it's in an infinite loop of reboots.
I cannot boot in safe mode: it just hangs with the progress bar showing 0%.
I rebooted to the recovery volume (which went swimmingly) and reinstalled the OS; this did the same thing: install, boot OK, restart goes into infinite loop of crashes.
I tried resetting the Parameter RAM. No change.
This is a 2009 iMac 27, 16 GB RAM, SSD & HD.
Thanks in advance for any help.
iMac, OS X El Capitan (10.11.1)
Posted on Nov 9, 2015 10:33 AM
Back up all data to at least two different storage devices, if you haven't already done so. One backup is not enough to be safe. The backups can be made with Time Machine or with Disk Utility. Preferably both.
Erase and install OS X. This operation will destroy all data on the startup volume, so you had be better be sure of the backups. If you upgraded from an older version of OS X, you'll need the Apple ID and password that you used, so make a note of those before you begin.
When you restart, you'll be prompted to go through the initial setup process. That’s when you transfer the data from a backup.
Select only users and Computer & Network Settings in the Setup Assistant dialog—not Applications or Other files and folders. Don't transfer the Guest account, if it was enabled.
If the problem is resolved after the clean installation, reinstall third-party software selectively. I can only suggest general guidelines. Self-contained applications that install into the Applications folder by drag-and-drop or download from the App Store are usually safe. Anything that comes packaged as an installer or that prompts for an administrator password is suspect, and you must test thoroughly after reinstalling each such item to make sure you haven't restored the problem. I strongly recommend that you never reinstall commercial "security" products or "utilities," nor any software that changes the user interface or the behavior of built-in applications such as Safari. If you do that, the problem is likely to recur.
Before installing any software, ask yourself the question: "Am I sure I know how to uninstall this without having to wipe the volume again?" If the answer is "no," stop.
Never install any third-party software unless you know how to uninstall it.
Posted on Nov 9, 2015 11:41 AM