broken mouse in x session

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

Hi.  I'm experiencing technical difficulties, 
if you can help I'll love you forever...

I'm running what was CorelOS, pretty much converted to woody (remove
all the packages with "corel" in them, edit sources.list, then apt-get
update && apt-get upgrade).  My mouse doesn't work in X, much as if I had
the wrong argument to Protocol in 'Section "Pointer"' of XF86Config.  

Odd thing is, 24 hours ago it worked fine.  It stopped when I was apt-get
install'ing things left and right [1], so I'm not sure what triggered it. 
(it stopped working right after I installed ssh.  Hm.)  In XF86Config, the
Protocol and Device for the pointer (mouse) were "PS/2"  and "/dev/mouse"
(/dev/mouse isa symlink to /dev/psaux). In the console, gpm still works
fine, and it has the equivalent settings in its config file
(/etc/gpm.conf; device=/dev/psaux, type=ps2). 

I have a very normal, 3-button, contemporary-model Logitech mouse, with a
PS/2 connector.  In XF86Config, I tried changing the Protocol to (almost) 
everything listed in man XF86Config; and changing the Device to /dev/psaux
and /dev/ttyS[0123].  In short, I tried every suggestion I found in the
archives in debian-user and my head.  No avail.

I did find that changing Device to be "/dev/gpmdata" and Protocol to
Microsoft, MouseMan, or MouseSystems, it worked fine except my mouse's
middle button didn't work.  I use this button a lot.  I can
Emulate3Buttons, but it's not the same. 

btw, this seems independent of WM (tested with twm; and enlightenment,
both with and without gpm).

Thanks in advance.
Aaron

[1] CorelOS is OK, except for the packages it's missing on the distro CD.
Didn't even have emacs, for chrissakes...