EXS 24 Logic Sampler Users Group

I recently definitely turned to G5 (Dual 2.0 , 2.5 GB Ram) and OSX (10.3), with Logic 
Pro. 
I was using a Multi-EXS Drumset Program, and when I turned my separate outs to relative 
aux, something strange happened... When the Drum's track is selected, all appears 
normal, but when I select another track... Ouch!  All the instruments on Aux sounds like 
when your audio clock is completely out, and the sound is bit-crushed. Also, the time 
response of the samples is a little bit up, anticipating the beat... The sensation is that aux 
are excluding the Audio-card latency (MOTU 828 MKII) and playing off-sync and off-clock. 
When I select the Drumset Track (where there's the EXS plugIn), all sounds normally.
I know for sure that in record and playback mode, the selected Instrument is processed by 
CPU1, and when you change the selection, the track is processed by CPU2. I'm working in 
"Multiprocessor mode", so I can't find a solution...
Does anybody gets the same trouble?

Danilo