screen seizures

My iMAC (intel) has been having "seizures" where the screen flashes and if I drap my opened windows around the screen I end up with repeated verisons of that window streaking across the screen. Eventually the whole computer freezes; I can't even shut it down. I force it to shut down via the poswer button. It seems to be related to my external hard G drive. When time machine backs up, the seizures begin. I think the frquency of the seizures has increased. Does anyone have the same condition? How do I stop this from occurring? Any help would be appreciated

Keynote-OTHER, Mac OS X (10.6.8)

Posted on Feb 13, 2013 1:25 PM

Reply
1 reply

Feb 14, 2013 2:36 PM in response to nicole from buena park

Hi Nichol, does it never do it if you disconnect that drive?


Have you blown the dust out lately?


Get Temperature Monitor to see if it's heat related...


http://www.macupdate.com/info.php/id/12381/temperature-monitor


One way to test is to Safe Boot from the HD, (holding Shift key down at bootup), run Disk Utility in Applications>Utilities, then highlight your drive, click on Repair Permissions, Test for problem in Safe Mode...


PS. Safe boot may stay on the gray radian for a long time, let it go, it's trying to repair the Hard Drive


Reboot, test again.


If it only does it in Regular Boot, then it could be some hardware problem like Video card, (Quartz is turned off in Safe Mode), or Airport, or some USB or Firewire device, or 3rd party add-on, Check System Preferences>Accounts>Login Items window to see if it or something relevant is listed.


Check the System Preferences>Other Row, for 3rd party Pref Panes.


Also look in these if they exist, some are invisible...


/private/var/run/StartupItems

/Library/StartupItems

/System/Library/StartupItems

/System/Library/LaunchDaemons

/Library/LaunchDaemons

This thread has been closed by the system or the community team. You may vote for any posts you find helpful, or search the Community for additional answers.

screen seizures

Welcome to Apple Support Community
A forum where Apple customers help each other with their products. Get started with your Apple Account.