EXS 24 Logic Sampler Users Group

Hi all,
I'm using a 1ghz TiBook, 1gig ram with a Digigram Vx pocket.  I have 
fast external drives that contain my audio files and samples.  The Vx 
pocket has been a little trogan and I've used it for years.  But I'm 
having frequent audio overruns as well as Disk I/O failures recently.  
The music is orchestral....the instruments are large....  GOS, Sam 
Brass, Dan Dean Winds, Post BOS290 etc.   I'm not a techie.... I'm not 
even sure I spelled it right but could my audio card be causing these 
problems....or I guess the better question is....What is the most 
probable cause of these problems?  When I look at my system 
performance....the "audio" side is maxed out...it chokes.  So...I 
freeze some files.  Almost imediately the Disk I/O is maxed.  When I 
Solo the "frozen" tracks... no disk labor.  When I mute the frozen 
tracks....the Audio side is at manageable  levels.  But when I un-mute 
the "frozen" tracks I get Disk I/O failures.  Then I unfreeze the 
tracks....Audio overruns.   I would really appreciate some insight into 
this.

Thanks in advance,
julie