I have a 2.4 Ghz MacBook Pro (4GB Ram, 256 MB video card). I have OS X 10.5.1 clean install. Within the last couple weeks I have noticed that if I play 720p or 1080p video files in quicktime that the frame rate is noticeably decreased, you can see that the movement is not very smooth. This goes for WMV and Quicktime files. I have restarted the computer and repaired permissions. If I look in activity monitor, there are no processes running with substantial CPU usage. If I look at the movie inspector while the video is playing, it says that it is at the encoded FPS (i.e. if the video is at 24 it fluctuates at or above 24 for playing FPS), even though it is clearly not that high. Anyone have a similar issue or suggestions on what I can do to correct this? Thanks much.