12.04 Dell Inspiron 5150 Reboot instead of Shutdown

[JackAndBlues]

Hey Guys,

my problem is the following: When trying to shut down the system, it reboots instead. There is a short moment when the computer has no power between shutdown and reboot.

System:
Dell Inspiron 5150
Ubuntu 64-Bit 12.04 (I just installed Ubuntu on the system; there has never been a normal shutdown with it so far)
Bios A02 (latest version)

Measures so far:
shutdown now, init 0 have the same effects.
I updated the BIOS only to realise that A02 is already the latest version. It changed nothing. I changed my default Grub entry in /etc/default/grub
to
GRUB_CMDLINE_LINUX_DEFAULT="acpi=noirq quiet splash", nothing.
I also searched Google for "ubuntu 12.04 restart instead of shutdown" but none of the posts could help me so far, please note that most of them redirected to this forum.

If you need any further information, feel free to ask.

Thank in advance,

JB

[JackAndBlues]

The problem is still on. I found out today that it is somehow related to the onboard-network-card. I can turn off the nic in the bios and it will shut down successfully eliminating the possibility to connect with the network of course. This seems a linux problem as Windows 7 is able to shut down the computer properly while Ubuntu 12.04 and Linux Mint fail to do so.

These two pages have helped:
http://forums.linuxmint.com/viewtopic.php?f=49&t=118094

The page above mentioned a workaround by right-clicking and disabling the network. I was using Xubuntu 12.10 and it did work for me.

http://en.community.dell.com/support....aspx#18132549