Troubleshooting case: Fixing a blue screen issue in OS X
There's a bug that results in Macs showing blue screens can be rooted in numerous areas. Recently a MacFixIt reader had such an issue and found the problem to be from a seemingly unrelated aspect of his system.
Many times problems arise in our systems that, though similar to those others are experiencing, are unique to our setups.
For example, some users may find that when using their systems the computer suddenly shows a blue screen. In some instances this may require restarting the computer and in others it may result in an automatic restart or a forced log-out, losing the system's data. Unfortunately blue-screen issues are rather general symptoms that can include numerous possible causes.
This type of problem is likely rooted in the handling of graphics or in critical processes that handle the log-in session, such as the window manager or the log-in window process--associations that can even be seen under normal system behavior. For instance, when you log in to your system, the screen may turn blue briefly as the window manager activates and configures your window session. Additionally, when you attach secondary monitors or otherwise adjust display settings, the system may flash a blue screen while the graphics system is adjusted.
Knowing or at least suspecting these OS components as the features being affected by the problem is a convenient step in the right direction, but isolating what exactly is triggering the problem is a bit harder to do.
Recently I was contacted by MacFixIt reader "Alan M." who was experiencing a problem with blue screens:
Basically, my screen goes totally light blue. I have to restart the computer by Control-Command-Power to shut it down and then Power to restart it.
The key observation here is that Alan was able to pinpoint when the problem began, which helps determine what changes to the system might have taken place. This information also helps if you have Time Machine active, because at the very worst you can restore the system to a backup instance right before this date and see if the problem continues.
Alan also mentioned that the changes he made to the system right before this problem started was to update Firefox, the Adobe Flash plug-in, and also installed the Thunderbolt software update from Apple; however, he had used the system for a week with these updates applied before the problem started.
The use of the system for a week suggests the immediate application of these updates was not the cause of the problem, especially presuming Firefox was regularly used to view Flash content (which is nearly impossible to avoid these days). Therefore, it is likely that the updates themselves were not responsible for the problem; however, it is good to still keep them in mind. Adobe Flash is used to present a lot of graphics content and interfaces with the graphics system to accelerate this process, so even if it alone is not responsible for a graphics-related problem, it could be conflicting with other plug-ins or system features that are causing the problem.
Additionally, the Thunderbolt update also may not seem relevant (Alan even mentioned he does not use Thunderbolt); however, something to keep in mind about this is that Thunderbolt interfaces directly with the graphics system and provides DisplayPort protocols over its bus. Therefore it may be a contributing factor.
As a first step in approaching this problem, I recommended that Alan run a general maintenance routine to clear caches and temporary items that OS X uses to optimize performance. Corruption or misconfiguration in these items can result in odd system behavior, including crashes of individual processes that the window session or graphics system may rely on. In addition, whenever problems like this occur I recommend people run through basic OS X troubleshooting steps to see if the issue shows up in various system configurations such as safe boot, or if you create and load a new user account. These routines also cover user-manageable hardware resets such as PRAM and SMC settings, which may contribute to odd system behavior.
These general maintenance and troubleshooting routines are not intended to be fixes to problems, but should help isolate when and how the problems are occurring. After performing these routines and observing the problem a little more, Alan found that the blue screens seemed closely associated with his use of Firefox. While a bit random in nature, when they did happen it was when he was quitting the program, suggesting this program or a feature of it was the root cause.
Generally when programs like this cause problems, you can try clearing preferences for them, uninstalling and reinstalling them, or updating them; however, Alan had already updated the program and Firefox is a well used program that is not known to have this problem by itself on the Mac OS. Therefore, it suggests a plug-in or add-on to the program may be involved in the issue.
Realizing this, Alan looked at his browser configuration and realized he had the "BetterPrivacy" add-on for Firefox, which was configured to run various routines when Firefox was quit. Though BetterPrivacy is mainly a cookie management tool, it interfaces with Adobe Flash and manages Flash-based cookies (keep in mind that Alan had also updated Flash in addition to Firefox).
With this information, while one option would be to disable or uninstall the BetterPrivacy plug-in, it turns out that Alan's version of the plug-in was out of date, and installing the latest update increased compatibility with his Flash and Firefox combination, resulting in the problem being cleared.
Overall this troubleshooting scenario demonstrates that although a problem might at first appear to be a deeper issue with a graphics system or with the stability of the system in general, it may be a more superficial fix that can be rooted out with some basic observation and observance to detail.
Do you have a similar troubleshooting scenario? If so then let us know in the comments.
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