Thank you for your post, I have been looking to see if anyone has had similar problems with connection loss. After looking through public resources and not finding the information I was looking for I looked into previous support queries and it seems we have had a customer with a similar issue and this was partly due to firewire bandwidth.
When configuring your system and setting up the external wiring you should have the option to input the signal through the firewire bus on the motherboard or going through a PCI/PCIe to the motherboard. It is recommended to do the latter because if the firewire bus is shared communication could drop especially if you were attempting an image acquisition. The concern is the bandwidth on the firewire bus may be too great with the camera and motion card together.
I hope this helps you with your troubleshooting, please get in touch if you have any queries.
Stephanie L Applications Engineer National Instruments UK and Ireland