I had the same problem.
I solved removing the firewire from my Cinema Display and connecting my iLink directly on my CPU.
Hope this helps…
My specs:
Mac Pro 3,1 Dual Quad-Core Intel Xeon
4 gig of RAM
FCS 2.0 with all of the latest updates.
Mac OS X 10.6.4
Sony HVR M15U (Digital HD Videocassette Recorder)