Sonar 8 Producer

Hi. I've got Sonar 8 Producer Edition and, as I am new to this software, I tried to start with something easy: I loaded a midi file of Star Wars (with all its tracks) and then I loaded into the synthesizer rack several instances of EWQL Symphony Orchestra Gold XP to assign the instruments, with 4 instruments per instance and 64 voices of polyphony for each instrument. The problem arise when I tried to play everything. A lot of voices were missing, and I even got strange noises at times. I've got a pretty good equipment (Quad 3.4 GHz, 4 GB RAM) and it never reached 10 % of processing load. So, where's the source of the problem? Maybe Sonar has limited polyphony? Thanks in advance.