I've been going to the mattresses for the last couple of weeks with my PIII600 computer, Win 98se & 2408mkII. There had been a constantly recurring error message in Sonar referring to Tdif Outputs 1 and 2 being unavailable due to being in use by another application. Of course, there was not anything else running when this would happen, and I had totally stripped my OS to the bone for audio optimization back when I set it up. So...I finally gave up on Sonar and went back to good old Cubase 5.0. Lo and behold - same problem...according to the 2408 support files over at MOTU's tech site - there is a similar occurence with Mac's ...The only thing I can ascertain , so far, is that perhaps you shouldn't have wave drivers and Asio installed at the same time. Of course, I'm not sure of this, because I can't get in touch with Motu tech support... If anyone has a clue, I'd love to hear a fix for this problem.