The intel8x0 driver doesn't support the MCP55 audio on the nForce 570 sound card. The PCI ID info is basically missing. I reported it upstream and am including the URL. I also provided a patch.
Created attachment 90650 [details, diff] intel-nforce-mcp55.patch
Will take care as soon as I fix this crash of kaffe :P
Committed in 1.0.12_rc1-r1.