"S" key does not work in X11 (XQuartz) The S key seems to be mapped to an incorrect value in XQuartz for me.  I am running OS X 10.7.5 and XQuartz 2.7.4 (xorg-server 1.13.0).  The problem also occurs in X11.app (XQuartz 2.6.5, xorg-server 1.10.6).  I am also running Homebrew  0.9.4, if that makes a difference.

Pressing S in X has never worked correctly for me.  In most applications in X, pressing S has no effect.  It may actually be mapped to a meta-key, because pressing S in some contexts (e.g., in most save dialogs) seems to trigger button hotkeys.  If I copy the "s" character from within a native Cocoa application and then paste it into an X application, that works fine.

Update: xev reports the following when S is pressed:

KeyPress event, serial 34, synthetic NO, window 0xa00001,
    root 0x281, subw 0x0, time 2057519943, (138,-10), root:(158,32),
    state 0x0, keycode 9 (keysym 0xff1b, Escape), same_screen YES,
    XLookupString gives 1 bytes: (1b) "
mbLookupString gives 1 bytes: (1b) "
FilterEvent returns: False

KeyRelease event, serial 34, synthetic NO, window 0xa00001,
    root 0x281, subw 0x0, time 2057520022, (138,-10), root:(158,32),
    state 0x0, keycode 9 (keysym 0xff1b, Escape), same_screen YES,
    XLookupString gives 1 bytes: (1b) "
FilterEvent returns: False


Update 2: xmodmap reports:

shift       Shift_L (0x40),  Shift_R (0x44)
lock      
control     Control_L (0x41),  Control_L (0x43),  Control_R (0x46)
mod1        Mode_switch (0x42),  Mode_switch (0x45)
mod2        Meta_L (0x3f),  Meta_R (0x47)
mod3      
mod4      
mod5
It appears that s has been mapped to Escape.

I don't know how it got be like this. I also don't know how to reset the map, given that setxkbmap -layout us (recommended by https://askubuntu.com/questions/29603/how-do-i-clear-xmodmap-settings) does not work. (It doesn't work for me either.)

So, as a last resort, if the only problem is s, then try

xmodmap -e "keycode   9 = s S ssharp Iacute"