Guitar FX BOX 2.6 Excessive delay

In Addition to my last message, When I run the program under Athlon XP, the operating system was WIN XP SP2 too. The same of my CORE 2 DUO! Before the Athlon, I had an AMD K6 II 350 with Windows 98. I was using the same sound card I'm using now on my CORE 2 DUO and the program run with no delay ( at least with a setting of low sample rate, no 16 bit, no stereo and no filters).