Some possible ideas:
Go to device manager and select your IEEE 1394 controller.
Right click on properties. Check device status--should be working properly
Check driver and see if there is an update if so install it. If the update doesn't solve your problem, roll back and then look at the websites below.
Click on resources and check to be sure that there are no conflicts
Chick on power management and make sure that you have not checked allow the computer to turn off this device
Firewire on Windows7 can be a problem generally associated with the MS drivers.
Try these websites for help http://social.technet.microsoft.com/Forums/en-US/w7itprohardware/thread/65cb7a25-2a84-4875-aa27-b084537e8da1/
long thread probably a good starting place.
This website offers a solution that may work for you http://www.studio1productions.com/Articles/Firewire-1.htm
. It suggests you use the legacy firewire driver.
Microsoft has a whitepaper on IEEE1394 at http://msdn.microsoft.com/en-us/windows/hardware/gg454502.aspx
might have useful information for you.http://www.sevenforums.com/
Good luck and have fun.