my iMac freezes and goes white
I have a 27 inch iMac which I bought in 2010. recently when I try and view either a video clip or anything from the Internet the screen freezes and goes white. I can restart it by pressing command shift P and R. this fixes it for a while but the screen goes blank after a few days. more importantly it freezes almost instantly while watching a video.
iMac, Mac OS X (10.6.8)