Digital BW, The Print

Hi

someone here (or on the 4000 group) posted that they used USB for QTR and Firewire for 
the Std Epson drivers (on the 4000 I think).

Could you please email me?  I have  a problem:  when BOTH cables are plugged in at the 
SAME time, my roll printing on the 4000 goes south.  I deleted QTR in Print Manager with 
the same result.  

Am I doing more than one thing wrong?  :)

thanks
Scott