Random Mac Pro users get the boot in Mountain Lion

Some users of Apple's latest OS X, Mountain Lion, have reported being randomly logged out of their sessions, with a conflict with dual graphics processing units (GPUs) being blamed for the problem.

 

The conflict may have caused a window server crash that forces users back to the log-in screen, tech site CNET reported.

 

It cited complaints by users who said the Mac would quit all running applications without warning and bring them to the log-in screen.

 

It said crash logs showed the problem stemmed from the window server handling certain graphics functions.

 

"While this may appear as if the system has restarted or even performed a standard log-out, the system is in fact experiencing a crash in a critical process called the Window Server that supports the current log-in session by managing the drawing and representation of windows on the screen," it said.

 

It added the problem may be due to some advanced desktop management features such as Expose, Missions Control, or switching between multiple desktops.

 

On the other hand, CNET said those reporting the problem so far have been found to have multiple monitors attached to more than one GPU in their Mac Pro systems.

 

"In testing, those who have switched to using just one video card either by unplugging monitors from the second card or removing it from the system have found when doing so the problem disappears," it said.

 

Also, it said those who booted the system in Safe Mode, which loads only basic drivers and disables graphics acceleration, said the problem does not persist.

 

CNET aso said a clean install of OS X by formatting the hard drive and reinstalling showed no change, hinting a software configuration issue is not to blame.  — TJD, GMA News