are hard drives running off bus power or have their own power plug? should have their own for capture.
you might want to try a firewire repeater hub as well.
http://www.bhphotovideo.com/c/search?Ntt=Kramer+VS30FW+4-Port+FireWire-800+...
this will also protect against burnt firewire ports.
MacPro4,1 2.66GHz 8 core 12gigs of ram. GPU: Nvidia Geoforce GT120 with Vram 512. OS X 10.6.x; Camcorders: Panasonic AG-HPX170, Sony Z7U, Canon HV30/40, Sony vx2000/PD170; FCP 6 certified; write professionally for a variety of media; teach video production in L.A.
