EXS 24 Logic Sampler Users Group

Anyone here using Sampletank & EXS24 without problems?

I load ST2 into audio instrument 1 (midi Ch 1) - I load in a piano 
from sonuc synth - name it Piano
put an EXS24 sampler on Audio Instrument 2 (midi CH 2) - load in a 
drum kit - name it Drums
In the arrange window I select Piano for track 1
i play & record piano onto the track
The recording plays back ok
In the arrange window I select Drums for track 2
I press play
I get ASIO : Overload message

I select Piano in the arrange window again
I press play
The recording plays back ok

The piano track will only play if its track is selected
If the piano track is not selected I get ASIO : Overload message

Result: I cannot play or record any other midi parts with the ST2 
piano track playing

This occurs at all bufer sizes 64...8192

Motu 2408
ASIO Driver is PCI-324 Driver2.0
Beige G4 dual 1Meg Ram
Virtual memory off
OS 9.2.2
Sampletank 2.0.6 OS9 VST version
Emagic AMT8 midi interface
Logic Audio Gold 4.81 (EXS Version)