Hello everybody! This is my first post. Sorry it has to be about a difficult, no-good issue with my Macbook Pro running OS X 10.10.5 (Yosemite), although I believe this applies to other versions as a friend of mine has virtually the same issue. For a few months now I've had a problem where, after anywhere from 6 hours to 36 hours after a system reboot, my mid-2012 13" Macbook Pro (OS X 10.10.5) will start to heat up, the fans become loud, and the system becomes unresponsive. The "Activity Monitor" application and "htop" display loads well above 200% (that is, consuming more than both cores of its Core i5 processor) and the battery will start draining very quickly until I kill the applications that are hanging and eating all the CPU. The applications are exclusively shell applications - that is, applications you would normally run from the Terminal or that would be launched in the background by crontab - and are often the same few suspects: bash, cat, sed, find, groff (when trying to open a man-page with 'man'), etc. These applications will hang every time they're run UNTIL a system reboot at which point things will work fine again. This is a very serious problem because many critical system features including installations and daily maintenance tasks launched from crontab depend on these programs. I did some digging and DTrace'ing when I found that not even a shell would launch under Terminal unless I hit CTRL+C during its load (at which time it didn't finish loading it's ".profile" or "rc" files) and discovered that /usr/libexec/path_helper was hanging at the launch of each shell process. I replaced path_helper with a program that simply exits and, now while the shell will launch fine, the same programs such as 'man', program installations, VMWare Fusion virtual machine loads (because of what's going on in the background), etc. will hang. I can kill the processes causing the problem and get VMware to loads its VMs from time to time, but other things just break. I am at an absolute loss for WHY this is happening. It doesn't seem to have any rhyme or reason. At first, it seemed to only happen when Dropbox would run with the presence of a symlink to an encrypted volume mounted in /Volumes/. I fully uninstalled Dropbox, removed symlinks and rebooted and things seemed fine for a few days. There, I thought - it was Dropbox being buggy and corrupting something. But alas my fortune was not to last long for the same processes started hanging yet again. I have no idea what causes this. Again, a reboot will alleviate things for several hours but invariably after no longer than 36 hours or so things return to their home in Malfunctioningville. The odd thing is that my friend experiences similar behavior. His laptop is a much newer 2015 Macbook Pro model and he runs either El Capitan (10.11) or macOS (10.12). He too thought it may had been Dropbox and after an uninstall of the suspected culprit, just like my experience the problems persisted. Anyone have any idea what could be causing this? Could it be some library that becomes corrupt over a period of.. wait, that doesn't make any sense. Seriously I'm at a loss. I've DTraced things down to the system call level to see what libraries were being loaded or what was being execve()'d and whatever else was happening just prior to the hang and cannot really find much consistent except path_helper (which again has been replaced with a binary that just calls exit(0)) would hang and a select set of shell tools/programs hang. As for other solutions I've tried running software like "Applejack" to check and fix permissions, corrupted caches/plists, defunct/non-existent links and system service / plist / launchd / library entries, etc. and, while that took care of some other slight nagging issues I had with my Mac, it didn't fix this. (I ran Applejack both with the system running as normal AND as single-user mode as instructed). Has anyone had a similar experience? Anyone know what in the hell could be going on? I'm at a complete loss here. Thank you in advance for any ideas / support!