Thanks Kevin for your detailed answer.
I have separated my boot disk from my data drive. I have 2-1Tb drives raided as my boot drive and photo work, and the other 2-1Tb drives raided for video work.
I have tried the purge after 20 frames on the secret menu with no luck.
I have played with the RAM cache, again with no luck.
I am thinking of upgrading but hate to do it in the middle of a project just incase there are problems. That will be my last resort.
I still can’t get more than three separate videos to play within the comp at a time. Three works fine. More than three and the freezing and stuttering happens.
What I’ve resorted to is to create the video wall in batches of three and then pre-render. Then I take three batches of three videos and pre-render again. I end up with 9 videos playing with in a single rendered video. Lots of work though. Really frustrating when I think I have the power to build it straight.
Thanks again for your thoughts.