Avid Pro Audio Community - Display stuttering, timeline shaking, visual delay

Hi - Mac osx 10.5.8 2 x 2.6 dual core 6 GB ram PT LE 8.03 cs update

Never have problem before but now my display suddently studdering,
or shake when I do some kind of command. I have a visible delay on my timeline when I try to move a region, I move it with my grabber and the action have a delay, maybee 1 -2 second. The same happen if I use shortcuts, like zoom in/out

I have all the latest update, even try to reinstall everything from 8.00 to 8.01
to 8.03 plus cs update. Even I´m not running quicktime, video I have this problem.
I even reinstall my mac osx system.
Hmmm..,I never have this problem before, my PT used to run very smooth whit no problems. But this is a problem, I do most editing, not music, and this really slow down my work a lot. You can not scrub very well (it jump in randomly small steps). I do hope that DIGI can solve this problem.
I´m losing work, because Im losing time and this is my work.
Yes I have several times trash my plist, DAE, ect. and try to remove all my plug ins, emty trash and restart, nothings help. !!!!
It is not the disk where I have my project, because I have a Back up on another Lacie Firewire disk and running the session from there wont help.
Need help. I could once again make a complete reinstallation, but I don´t
think It will do any good.
What is very strange is that new project run smooth
but a lot of project I made the last two weeks are affected by this.
So Please...DIGI...thanks.