Macbook, Snow Leopard, Pro Tools 8 Firewire Conflict

I apologized in advance if this issue has already been posted, but I was unable to find it using the search function.
I have been getting a 6101 error while running M-Powered Pro Tools 8 (8.04)using 2 different M-Audio Firewire Interfaces (Firewire410 and Profire 610). I am only playing back 3 audio track w/no plug ins. CPU usage hasn't gone over 5% and I am getting a Hardware Buffer Error, whcih I have changed numerous times to no avail. I have a new, clean install of Snow Leopard, ProTools, and Interface Drivers with all of the latest updates. Hardware Settings: (1024 Samples, 1 Processor, 95% CPU Available)
However, I tried the M-Audio Fast Track Ultra USB 2 interface and have had no issues. I have ran through the session over 15 times and haven't had a crash.
Is there any known conflict between Snow Leopard, the firewire drivers and, the latest ProTools/M-Audio components? And, is there a workaround/new firewire driver that will fix this problem??

Thanks,
JIM

Black Macbook
2.15GHZ Intel Core 2 Duo, 2GB RAM
Snow Leopard 10.6.4
M-Powered Pro Tools 8.0.4