Let's not get distracted by hardware certification. The SC420 has 3 PCI slots and the bad behavior of the board happens in each one of them. The A1200p is not on the list you sent of hardware certified by Trixbox either. Let's try to debug this problem and solve it.
The problem with the card (buffer re-sync) was there without trixbox on a straight debian build. I tried trixbox to see if their package would relieve the problem. It did not.
I've already sent ssh info to your email.
Please try to see what is causing the board to generate these messages and the accompanying loud clicks. It is not usable in this condition. Do you have any diagnostics you can run on it?
