Video playback becomes slow and jerky.

[hedgerocks]

Pro Tools 10 running on Mac OS Lion.
4 x 2.88 GHZ Quad Core Intel.
My session i dedicate 15 processors to pro tools. Leave one processor for the OS. CPU usage limit at 99%

Heres is my process for importing a video into pro tools. Convert to DV-Pro NTSC. Defiantly not an H.264.
Move to a dedicated drive for videos. Not on the same drive as my pro tools sessions or the OS.

Keep in mind these videos are never really longer then 90 seconds. and not that large in size to begin with.

I then move the video file to my second monitor and "fit to screen".

Typically everything works fine for a little while. Lets say an hour or so. But then the video starts playing back stuttery. Jittery. Whatever you want to call it.

This bogs down the session. Makes playback impossible.

I'll blow out the prefs.

That sometimes helps.

I'll restart the system.

That sometimes helps.

But there really does not appear to be any rhyme or reason to it. Sometimes everything works fine. Other times it craps out. This is unbelievably frustrating.

I've searched the DUC and various forums and just can't seem to make sense of it all. there appears to be a a lot of conflicting solutions. If one at all. Is there a definitive answer? Something I'm doing wrong?

Please help me geniuses of the internet.