SIGSEGV (11) usually leaves a useful core dump. It might help to look at that if debugging symbols were compiled into the xserver. Thats something someone at nvidia should look into. I have no idea (nor do I care) how to begin to debug an xserver. I've got the agp warning as well, and 16 of the GetModeLine entry pairs at the bottom of my log for a working xserver--been up a couple of days now. It's a bit of a shame that noone from nvidia has responded to any of this. We don't pay for the drivers, but we pay loads of money for the graphics card. I get better support from gpl software.