After upgrading to the 275.19 driver, many Gtk+ and Gnome applications fail to terminate and go into an endless loop, using 100% of the CPU. For me (I am using Gnome 3), the applications affected are gnome-session and gnome-settings-daemon. Other people have reported similar problems with blueman, fusion-icon, gnome-terminal, lxterminal, and sakura. See https://bugs.gentoo.org/show_bug.cgi?id=375615
The fact that gnome-session and gnome-settings-daemon are affected is particularly critical: it makes it impossible to log in with gdm-3 (which starts a gnome-session process of its own). Even if you use another login manager, gnome-session going into an infinite loop when terminating makes it impossible to log out of Gnome.
When connecting to one of the affected processes using gdb and getting a backtrace, it becomes clear that the Nvidia driver is the culprit:
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
17515 gdm 20 0 415m 29m 17m R 100 0.4 3:49.47 gnome-session
17522 gdm 20 0 548m 33m 22m R 100 0.4 3:49.65 gnome-settings-
# gdb -p `pidof gnome-session`
#0 0x00007f1fdcd17ba4 in _nv012tls () from //usr/lib64/opengl/nvidia/lib/libnvidia-tls.so.275.19
#1 0x00007f1fe06f46ed in ?? () from //usr/lib64/opengl/nvidia/lib/libGL.so.1
#2 0x00007f1fe06d3eb9 in ?? () from //usr/lib64/opengl/nvidia/lib/libGL.so.1
#3 0x00007f1fe54ca26d in _dl_fini () at dl-fini.c:249
#4 0x00007f1fe209b351 in __run_exit_handlers (status=0, listp=0x7f1fe23e64c8, run_list_atexit=true) at exit.c:78
#5 0x00007f1fe209b3d5 in exit (status=<value optimized out>) at exit.c:100
#6 0x00007f1fe2084fb4 in __libc_start_main (main=0x40cdc0 <main>, argc=4, ubp_av=0x7fffc3c59b28,
init=<value optimized out>, fini=<value optimized out>, rtld_fini=<value optimized out>,
stack_end=0x7fffc3c59b18) at libc-start.c:258
#7 0x000000000040d341 in _start ()
And indeed, downgrading to the 275.09.07 driver fixes all problems.
Potentially relevant information: my card is a GeForce GTS 250; I am using Gentoo (~amd64), kernel 2.6.39, gcc-4.6.1, glibc-2.13, xorg-server-1.10.3, with gtk+-2.24.5 and 3.0.11.