If you're using a SB Live card, go to the control panel and open it's settings. There you'll find and option where you set how much memory soundfonts can use. Raising this value should do the work.
I am using cakewalk pro audio 9. Sampler ? Many...actually I think it doesn't matter (I'm not sure), any size of .wav files I try to import it doesn't work..even if it's a 100kb.
By the way: What's the relation between cakewalk and sonar ? What is sonar anyway ?
A sampler is any program that make .wav files for music ?
Thank you both, later I'll try to raise the memory for soundfonts.