Mouse Scroll Wheel Activates Context Menu In Firefox

[Hal Vaughan <hal@thresholddigital.com>]

I just installed Sid to a new partition on my hard drive.  I had trouble (as 
posted eariler) with the mouse movement being jerky under the 2.6.8 kernel.  
I replaced that with the 2.6.15 kernel, which I understand was packaged under 
a new kernel packaging system.  The mouse movement is no longer jerky under 
KDE (with X.org), but I had, and still have, to a small extent, a problem 
with the mouse scroll wheel.  I'm not finding anything useful on this.

When I first booted with the 2.6.15 kernel, I was glad to see the jerky mouse 
movement was gone, but when I used the scroll wheel to scroll up or down in a 
window, the down scroll worked, but the up scroll would always bring up the 
context menu.  A right click also brings up the context menu, as it should.  
This happend in all KDE windows and in Firefox.

I edited /etc/X11/xorg.conf and added this line to the mouse config section:

Option "ZAxisMapping"   "4 5"

actually, at one point, xorgconfig had used another line:

Option "ZAxisMapping"   "4 5 6 7"

This fixed the problem in all KDE windows, but not in Firefox, where I use 
this quite frequently while reading web pages and man pages.  Scrolling down 
is no problem, but scrolling up always brings up the Firefox context menu.  
If I right-click first, the context menu comes up, and if I hold down the 
right mouse button and scroll while that button is down, I can scroll up and 
down all I want.

If this happened in all windows, I'd think there were a problem with mapping 
the buttons in xorg.conf, but the only window with this problem is Firefox.

Any ideas what is going on and how I can restore "normal" behavior where only 
the right mouse button pops up a context menu, instead of scrolling up doing 
it as well?

Thanks for any help!

Hal