Mouse buttons stopped working

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https://bbs.archlinux.org – I have a Logitech Marble Mouse (connected via a USB to PS/2 adapter).  It has no scrollwheel, so I set up the small "extra" pair of buttons to toggle "scroll mode" in certain applications (like Firefox & Chrome).  When activated, moving the trackball scrolls the page up/down/left/right instead of moving the pointer.It's been working fine for months, but a week or so ago, the scroll buttons suddenly stopped working.  The settings are contained at the very bottom of the file /etc/X11/xorg.conf.d/10-evdev.org, and the only other file in that directory m (HowTos)