Have you tested to use xev whit the mouse the first thing you do after starting x.
Also what is in your xorg.conf? I have a similar problem. I actually managed to configure my mouse to send the right events (6 and 7 in xev) but when i scroll the horizontal mouse wheel fast I stop getting 6 ad 7 and gets 4 and 5 instead. To me it looks as the reverse of the firefox bug linked above and I wonder if some fix to the above bug have caused this one. -- Side scroll wheel buttons mapped as wheel up/down https://launchpad.net/bugs/33404 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs