I have installed the 64-bit drivers as directed (Win7 64-bit machine running 2011b 64-bit) and frequently (but not all the time) get the error "Error using imaqdevice/preview (line 177) dcam: insufficient 1394 bus resources to complete the requested task". Once it has given this error, it will sometimes work again once I reboot, sometimes not.
I have also installed the 32-bit driver and running from Matlab 2011b 32-bit, but get the same result.
I have tried two different firewire cards, both with the same result. The same card worked fine in a (different) 32-bit computer running 2011b 32-bit with the 32-bit drivers.