"Audio device buffer underflowed. If this occurs frequently, try decreasing the H/W Buffer Size in the Playback Engine or remove other Firewire devices (-6085 or -6086)" during playback in Pro Tools LE 7.1.1.
Both buffer overflow and underflow errors were encountered during playback even with only 1 track in the session. Adjusting playback engine settings did not help. Additionally, an "Unable to locate digidesign hardware..." error occured when launching. After clicking OK, Pro Tools launched. The Digi 002 was powered on and connected when this message occured.
This occured with a Digi 002 and an MBox2Pro connected to the front Firewire Port of an Intel-based Mac Pro 3.0GHz running 10.4.7 (Tiger) and Pro Tools LE 7.1.1.
Moving the Digi 002 to the back Firewire port on the Mac Pro solved both problems.
IMPORTANT: Make sure to power down the Digi 002 before connecting it to the computer's Firewire port.
Please Note: Annecdotal evidence from different users suggests that this may not be true on all machines. The important thing to remember is that if you are experiencing the errors described when connected to a particular Firewire 400 port, try connecting using a different Firewire 400 port. Also, we have actually had opposite reports with PowerMac G5's - performance seemed to be better on the front Firewire Port of the PowerMac G5.