Originally Posted by dpw2atox
looks very similar to my setup, only difference is I don't have the hardware mouse setting but that shouldn't make a difference.
Ahah! This fixed it! Genius!
I've had this disabled since the days of animated Xcursors, because the NVIDIA driver used to shear them when HWcursor was enabled. Setting HWcursor to on completely fixes the renderaccel bugs (if you want to have some fun with your X server, set Option "HWcursor" "0"; it should lock up pretty quickly when you use xcompmgr).
So this IS a driver bug as I expected -- using SOFTWARE cursors and RENDERACCEL in combination creates the 100% deadlock; using both settings with acceleration completely fixes it.
Thanks a lot for your time, especially dpw2atox for bothering to review my config.
NVIDIA, read, learn, fix the problem.