Should I delete my Logic Express before I load Logic Studio 9 . No need for both programs I would think . Any tips of comments ?

Well, built-in audio drivers AND Airport is disabled and the problem persist.

I've got the "Error while trying to synchonize Audio and MIDI. Sample Rate 41599 recognized. Check conflict between logic Pro and External device." in a simple project with 3 audio channels and about 4 aux channels. A very simple project.
But I'm having well known System Overload errors in many projects, all kinds of projects.
An example of my basic project:
* A multi-output instrument channel for drums. I'm using Izotope iDrums for it because is more lite... Well I expand this multi-out to the 8 aux channels 642-901 but use about 6 aux only, one for kick, another for clap, hats, crashes..
* 6 instrument channels. 2 for basses... I get the error running lite plugins like V-station, Vanguard, EXS24, Albino, Blue...

* 4 audio channels to record my external synths. I've tunerd them of, also turnet the inputs of leaving only the output because I believe this takes cpu process while monitoring the external audio signal...

* 6 audio channels for effects that never plays at the same time, 642-812 maximun of 2 or 3 at the same time sometimes...

* 6 aux channels for delay and reverb and drums submix.

Well, I've this time only trying to run lite plugins like iDrums, V-station, Vanguard, EXS24, Albino, Blue. For effects I'm using one instance only of Arts Acoustic Reverb (this is not so lite) and one ohmboyz delay, the Voxengo ones, PSP (I only use lite PSP plugs and I'm not even using Vintage Warmer LE), well Logic compressor, Equalizer, N10-004 Enveloper and other lite things like the Direction Mixer...

I try to select the right sound and do lite process as possible... My channels strips almost of the time have only a Logic Compressor, Logic EQ, a kind of saturator like the Voxengo ones or PSP, sometimes another compressor for sidechain (I produce e-music), a send for the reverb or delay... Well that is... Nothing special and the Overload persist!

I noticed that this problem appeared after the Logic 9 or the 10.58 update. I don't know exactly when because I've inslaled these softwares almost at the same time... And installed againd yesterday, tookes one entire day ;/ (Man I'm tired...)

Well, simplifying: Is like the CPU is 40% heavier, n matter what I do, if I run a single instrument in a new project it's heavier, my old projects are impossible to play, and my new projects are more lighter because I'm using lite plugins and still get overloads.

Another thing is that there are some strongs CPU peaks.