After installing 970129, I couldn't use startx as it would display
a bunch of help text for "X", but not run.
Open your startx file (use "which startx" to find it)
and edit the line:
"serverargs="
It probably contains: "-optionmouse" to make the option key
unnessasary for using the pseudo mouse buttons.
Change this to:  "-nooptionmouse"
This was changed in the 970129 X11 update.
-Kenneth Lu, kenlu@mit.edu, 1/30/97