I am running Premiere CS5 on a Windows 7 4GHZ sandy bridge I 7 computer. I have no problems playing video of any type, with variety of players, or with Vegas Pro 10. Premiere Cs5 video preview plays smoothly with the exception of the CTI (current time indicator) looking like it backsteps (or jerks backward) a few frames at regular intervals. If I reset the CTI near a backstep point I can restart the preview and it will play smoothly over the previous backstep point, only to resume the backstep behavior at regular intervals about every 8-10 seconds. This behavior occurs with MXF, AVI, AVCHD video sourced from Sony NX5u, Canon Xf100, Canon G10, and others. Behavior occurs with or without GPU rendering enabled. Ouput (render export) from Cs5 to various formats looks and plays perfectly. So the backstep issue, while very annoying, is not evident in finished video. Cs5 has exhibted this behavior since installation a couple of months ago.

Any suggestions would be greatly appreciated, and thank you in advance.
Rick

I've seen it too from time to time. Please file a bug report on this: http://www.adobe.com/go/wish