I recently bought a new Fireface UC to work with Logic on my MacBook. (Mac OSX 10.5.8)  Unfortunately the sound is coming out only in quiet crackles from my speakers and headphones.  I went through a huge number of steps towards repairing this problem with a guy from Synthax, on the phone, yesterday, but, in the end, we were unable to repair the problem.  I tried the Fireface with another computer in the house, a PC, and the sound was actually fine, so it appears it is a problem with my computer, and I was offered the suggestion from a friend that it might be my old Digidesign/Protools software getting in the way.  (when I am playing a logic file, and the sound is sounding fuzzy, I also get the error message:  "Error while trying to synchronize audio and midi.  Sample rate 50003 recognized.  Check conflict between logic pro and external device.")

Please help me out!

Philippe