The Lumberjack wrote:
I can only surmise that one of the recent software updates taken has created this issue.
They may have done so only indirectly: software updates sometimes expose preexisting problems users aren't aware of. Examples:
• Minor file directory errors that become more serious (because updates replace a lot of files)
• Preference file ("plist") corruption that cause execution errors in update or application processes
• Hacks, system enhancers, third party drivers or firmware, etc. that do not fully comply with Apple developer guidelines or industry standards (like ISO, USB, etc.)
• Marginal hardware, either in the process of failing or slightly out of spec due to aging or insufficient quality control by the manufacturer
Some of these things in the latter two categories are especially hard to troubleshoot because they are evident only with upgraded system software, making it appear that the update itself is at fault. Worse, sometimes vendors blame each other or (when applicable) assume Windows compatibility is more important than general compatibility & refuse to investigate or correct a problem until it becomes blatantly obvious their product is at fault.
All users can do is eliminate what they can from the possible causes, like running Disk Utility to verify disks are uncorrupted, trying a new user account to see if a user preference or login item is at fault, trying a 'clean' system free of any hacks, enhancers, etc., unplugging unessential peripherals, & so on. If none of these things help, there isn't much left besides the update.