Problems with MBox 2 Pro and Mac OS X 10.4.9

[gazo]

I am having problems with my new MBox 2 Pro. When I try play audio files from finder, there is sometimes a delay, and sometimes the file does not play (no audio), the same happens in quicktime. The movie plays but the sound keeps coming in and going out. The unit also experiences similiar problems in FCP. I have had the unit a couple of weeks, and I dont think it was doing this when I first got the unit. My MBox did come with 7.1, and I upgraded it to 7.3 through to 7.4. I dont know if this is the problem. I dont really wanna downgrade and hope that it works, to find out that it may not. If there is something else that may be causing the problem, any help will be much appreciated.