Thanks Roman, that was actually the problem, i have /usr on a different partition and copying modprobe.conf to /etc/modprobe.d/ resolved the problem, but I've been using this partition layout for a long time and through different ubuntu releases and I've never had this problem before.
Thanks Roman, that was actually the problem, i have /usr on a different partition and copying modprobe.conf to /etc/modprobe.d/ resolved the problem, but I've been using this partition layout for a long time and through different ubuntu releases and I've never had this problem before.