I want to purchase one of the new aluminum imacs but am concerned about this freezing issue. I want to go with the 20" iMac. Is this problem with both 20" and 24" or just 24"? Also, I originally figured it was a driver issue but am now hearing it's a hardware issue. I've heard about some people taking it in for repair and getting a new graphics chipset. Has this been confirmed? I'd at least feel better hoping a new imac would have this newer chipset. For freezeups is this being only experienced with older 'new generation' imacs or is this also being seen with the latest purchases? When I buy I plan to go with refurbished. I'm hoping with refurbished they would be updated to any new graphics chips.