I have a rather serious shutdown/reboot issue with my Ubuntu OS on my brand new Dell latitude E7440 netbook. The issue does not seem to depend on the OS version: it occurs with 12.04, 13.10 and now with 14.04. I've waited for the new LTS in the hope that it would solve my problem, but that is not the case.

After shutting down my ubuntu, my laptop reboots about two seconds after shutdown. I've tried many things to solve it, but none of them did the job. I have the 64 bit version of 14.04 installed and boot in legacy boot mode with secure boot disabled. The behavior is independent from a power cable/usb device/ethernet cable being plugged in. Strange enough, however, it does sometimes stay powered off after being used for several hours...

I know there have been several treats concerning shutdown/reboot issues, but none of them provides an answer to my specific case. I ran diagnostics in the BIOS to recover any potential hardware problems, but there were none. If you have an answer or even a clue on how to solve this issue, it will be highly appreciated! Thanks in advance!