I have a Microsoft IntelliMouse Explorer mouse (wheel with two side, or thumb, buttons).

# cat /proc/bus/input/devices
I: Bus=0003 Vendor=045e Product=001e Version=0114
N: Name="Microsoft Microsoft IntelliMouse® Explorer"
P: Phys=usb-0000:00:1d.1-2/input0
H: Handlers=mouse0 event1
B: EV=7
B: KEY=1f0000 0 0 0 0 0 0 0 0
B: REL=103

I am running Mandriva 2006 Free and after updating xorg (via MCC) my side buttons suddenly stopped working (i.e. Firefox stopped recognizing them as forward/back buttons). After extensive searching and failed fiddling with xorg.conf and imwheel (not needed BTW) it dawned on me that xmodmap was not set up properly.
Under Mandriva xmodmap is called from /etc/X11/xinit.d/mouse_buttons
It was
xmodmap -e 'pointer = 1 2 3 6 7 4 5'
since this mouse has 11 buttons (as shown by xmodmap -pp)

# xmodmap -pp
There are 11 pointer buttons defined.
--snip--

I tried this instead
xmodmap -e 'pointer = 1 2 3 8 9 4 5 6 7 10 11'

Apparently, physical buttons 4 and 5 are the side buttons and the code for buttons 8 and 9 send the codes for <alt>-left and <alt>-right (back and forward). I assume this is correct because all the buttons now work as expected (even the wheel).

And, yes, it continues to work after a reboot.

Hope this helps.

thanx, good 2 know.

Thank you - I was just starting to get seriously annoyed at the loss of the buttons after an update to Mandriva 2006, and the lack of info through Google.

xmodmap -e 'pointer = 1 2 3 8 9 4 5 6 7 10 11'

Did the trick.

Thanks!

Mouse buttons all work again.