Re: BSOD with 6111
load the agp-module (or if it is built in, just boot). Do NOT boot into X! Let testgart running, look for errors in testgarts output and dmesg. This will test your agpgart, without hanging your box. Maybe it will garble your output, but than a second run will maybe clean it up (if it run, if your box crashes, it is definitive a kernel-bug).
This way, you will see, if it is nvidia's or the kernels fault.