Here's another tip from Daniel Fisher, Sweetwater's Director of Product Optimization:

One of the unique quirks of some computer-based software samplers is that they seem to glitch on the very first notes of the day, almost as if the computer has to clear its throat before flawlessly delivering your song.

If you're demonstrating a song to a client make sure that you've run the song once before letting your client hear it. It's easy for you to understand that it only glitches that first time, but it can be scary for your client who then worries that it's going to happen again.

If you have lots of songs, another easy fix is to create a sequence that plays every note of every instrument that you'll be using and run it right before you start working. The ideal speed and placement of the notes varies between systems and software, but it's easy to experiment to come up with just the right "warm-up" song.