Hi
Though more information is needed about your system, Pro Tools 6.7 is compatible with Mac G5 running OS 10.3.8. More information can be found at :
http://archive.digidesign.com/compato/osx/panther/hd/
There is no need to disable any sound card when running Mac OSX. More information for Mac optimization can be found here:
http://www.digidesign.com/index.cfm?...4&itemid=25629
Kindly