i am running xorg-x11 modular (7.0.0.rc2) however this problem already happened with other versions of X and other version of the NVIDIA driver (but just now I discovered the source of the problem). if I have the RenderAccel option turned on, launching firefox or thunderbird locks up X (i can just kill it with the SAK key) please, can someone confirm this behavior? my videocard is a NV18 (GeForce4 MX4000)
This is actually a known issue. There's not much that can be done about it until nVidia fixes RenderAccel or chooses to do things differently. Some sites do suggest playing with the NvAGP setting to work around this issue. Marking upstream since it's nVidia's problem.