Ta, does not really answer my question though
Anyway, I am beginning to think it is the sata_nv driver, nvidia have not released any info on it and it seems to be a best guess to make it work.
I have also discovered that the latency of the pci device for sata is set to zero, which means it give up the bus immediately, probably not good. The two pvr cards are set to 128.
I think I might need to change this.
AT the moment I am waiting for it to hang again, I have altered the cas/ras timing in bios to see if that helps, at the moment we have an uptime of 2 days so it is due to crash again.
I have not been using much in the last few days either.