I had the same problem with a Focusrite Saffire and Windows 7 64x, but just solved it through this forum. I did revert to the Legacy firewire driver and updated the firmware, but the computer still did not see the interface device. I read in one of the posts that someone had moved the cable from one firewire port to another and had it work. I tried this and it worked for me too. I realize this won't help if you only have one firewire port, and I have no idea why it worked (in fact I find it vaguely troubling that the solution is so mysterious; I don't know enough to know if it's conceivable that changing the legacy driver had an impact on only one of the two firewire ports). I thought I would confirm this solution in case it helps someone else.