Why does eth0 keep getting enabled periodically?

[mark0978]

I've included my network interfaces file. Periodically (every couple of minutes) my eth0 gets enabled which for some reason breaks networking. This is because eth0 is not connected to anything at the moment. The only way to fix it is to do the following

sudo ifconfig eth0 down
sudo ifconfig wlan0 down
sudo ifconfig wlan0 up
sudo route add default gw 192.168.0.1 dev wlan0

What process is causing this to happen and how do I stop it. I've noticed a similar issue when I'm wired and wlan0 kicks on. I think it has to do with multiple default routes when wlan0 is involved, but not entirely sure why it is failing now. Basically it ends up being unable to find the router (arp -an shows no mac address for the router). The steps above put it all to rights, but having to do that every 15 minutes or so is a PITA.

cat /etc/network/interfaces
# interfaces(5) file used by ifup(8) and ifdown(8)
auto lo
iface lo inet loopback

auto eth0
iface eth0 inet dhcp

#auto wlan0
#iface eth0 inet dhcp

[hal8000]

What version Mint are you using?
I used LM14 KDE on my laptop with eth0 and wlan0 and had no problems.

I've now installed LM16 KDE on my laptop and still no problem with wifi.
Ethernet is not used or plugged in.