I updated the BIOS after installing Win8 x64 succesfully,then I reinstalled Ubuntu 14.04.1,I am happy to report that the shutdown prolem is finally solved,thanks a bunch :)
although the BIOS update succesfully solved the situation,I will still post the outcome of dmidecode -s bios version and dmidecode -s bios- release-date V1.10 10/24/2014 ** Changed in: linux (Ubuntu) Status: Incomplete => Confirmed -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1427947 Title: unable to shutdown To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1427947/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs