I have been told to report this bug: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/921380 , here, I do not know if I am reporting it on the proper place or how is this suposed to be reported.
Yep.. although this appears to be a firmware problem. The kernel has some options to try different reboot methods which may help. You may find one of reboot=b, reboot=p or reboot =c helps. If so then let me know along with adding the output of "dmidecode" to the bug report.
ping...
Since no response for long time, close this bug as invalid. Please feel free reopen this bug if availabe.