Presonus Inspire 1394 audio interface problems with Macbook pro 13" 2.53ghz

Hey guys, I recently got a macbook pro 13" 2.53ghz and installed bootcamp with windows 7 ultimate 64 bit on it. When I tried to use my presonus inspire 1394 audio interface as the main source of my output on the windows side of things, there was a strange crackling noise that comes on every 5 seconds or so. As you all know the audio interface has a firewire 400 port whilst the latest macbook pro only has a firewire 800 port. So I had to buy a cable to connect the two together. I've used the audio interface very frequently and it has served me very well back when I was still using a pc. I had windows 7 ultimate 64 bit running on my pc and everything worked fine. Also a few days ago I tried the interface on my mates macbook white 13", which has a firewire 400 port, so I just used the original 6-pin to 6-pin cable that came with the interface. No crackling at all. I half suspect it might be the case of a faulty cable, but then I bought a firewire 9-pin to 6-pin male to female adapter and used the original cable and it still has the same problem. Might it be the firewire port that has the problem? Does anyone have any suggestions or advice? I'm a musician and have got lots of recording projects lined up and need this to work properly asap. Thanks guys.