Hi folks, I'm having a peculiar problem with my MBP and wonder if anyone has insight into this. I don't know when it started... but I now experience a momentary display freeze every 2 seconds under the following circumstances:

1. External monitor connected
2. Quick Time Player launched

the freeze is only momentary - it looks like video playback is stuttering... but it affects the entire screen and mouse refresh (and position) too and is very regular - in fact, it is exactly in sync with the Activity Monitor 0.5Hz refresh rate! Hmmm

If I quit QuickTime or disconnect the external display - refresh is fine and everything runs and looks smooth. But this is a real problem as I need 2 monitors and QT. I have not found a work around in any of the Apple forums or anywhere else.

Also... I'm pretty wary of downloading 10.6.8 - which seems to have a reputation for creating video problems rather than fixing them. Any opinions on whether it might make things worse or better?
thanks and cheers,
Phil

MBP 17" 2.66 i7, 8GB
OS 10.6.7
QuickTime Pro (7.6.6) - problem also occurs with QuickTime X
NVIDIA GeForce GT 330M
Dell 2407WFP 1920x1080 via Apple minidisplay/DVI adapter
automatic graphics switching [ off ]
spaces [ off ]

info update... using Quick Look (instead of Quick Time Player) to view movies - even in full screen on the external 24" monitor - is completely smooth*

*providing Quick Time Player is NOT open

another update... iTunes also causes the previously described display intermittency.