Sonar, and some other programs and devices, do not wake up well from sleep/hibernation, at times.
I always set everything to high performance power management options, and do not have issues - I am on my computer for an average of 14 hours a day, so it is not particularly any issue for me to have it set that way anyway.
When I DO leave the computer to do something, or sleep, I usually make sure I am out of Sonar, and if so, I then shut it down.
Bob Bone