Hi I recently purchased the top end 21.5 iMac (6770 graphics) and installed lion. When playing HD trailers from apples site, and sometimes flash video, I get random screen lockups, forcing a restart. I just wanted to know if anyone with the same machine is experiencing the same issue, or if my graphics card is screwed. I know it could be a driver issue with lion that's why I'm asking before returning the computer. All seems to be fine under snow leopard, but maybe lion is accessing certain parts of the card that snow leopard may not be? You'd think the drivers for the new iMacs would be optimized for lion already... All firmware is up to date.