This is actually common with PC Laptops - god bless them....
You may have an IRQ sharing issue, but it;'s also possible there are not enough resources on the built-in FW port to manage the bandwidth requires by such an interface as this.
BTW, have you tried
www.musicxp.net, checkout the Tuning Tips.
Not a bad idea to disable the 1394 Net Adapter from the Device manager.