make X messages more verbose

[Aaron Maxwell <amaxwell@phy.ucsf.edu>]

You know how when the X server starts with startx, it prints text to the
screen and more text to /var/log/XFree86.0.log?  Is there a way I can
make either or both more verbose (e.g. a debugging option)? 

Last night when I apt-updated my sid box, it replaced some of the X
libraries.  Today my X server won't start, but the messages emitted
aren't cluing me in.

FWIW, here's the tail of XFree86.0.log (the console output of startx is
the exact same, minus a few lines):

  from XFree86.0.log:
  (**) Option "Protocol" "IntelliMouse"
  (**) Mouse1: Protocol: "IntelliMouse"
  (**) Option "CorePointer"
  (**) Mouse1: Core Pointer
  (**) Option "Device" "/dev/gpmdata"
  (==) Mouse1: Buttons: 3
  (**) Option "BaudRate" "1200"
  (**) Mouse1: BaudRate: 1200
  (II) Keyboard "Keyboard1" handled by legacy driver
  (II) XINPUT: Adding extended input device "Mouse1" (type: MOUSE)

After this, the X server crashes with no further explanation.  Note that
kdm (and I'd expect xdm and gdm) seems to work perfectly fine.  Any
ideas?

Thanks in advance.
Aaron