So sorry if there's already the same exact question somewhere around the internet 
Resuming my situation, I installed Debian Squeeze on my system two days ago, using a wired connection to internet (which worked fine). After that, I had to install the non-free wireless package in order to scan wireless networks. It now works fine, and I can connect and get to internet. But with wired connection, i connect via eth0 and none of my applications work. And they're not in offline mode.
Also, i already went here: http://wiki.debian.org/NetworkManager and I checked if that was my case. I tryed what they say several times in some different ways, but I still can't connect. Even more, if I change something like they say, I get "unmanaged device" and I can't even connect to the internet. And the wired connection works, I'm using it right now on my ubuntu 10.10.
If you want more information, I just tried to ping sites like google.com or youtube.com using network preferences and it does work, it gets 100% of the packages back around 50ms later, so the internet appears to work. Also, when I connect via wireless, everything works perfectly.
If you need them, here are the contents of:
/etc/network/interfaces (it was like this after installation):
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).
# The loopback network interface
auto lo
iface lo inet loopback
# The primary network interface
allow-hotplug eth0
# NetworkManager
iface eth0 inet dhcp
and /etc/NetworkManager/NetworkManager.conf (it was like this after installation)
[main]
plugins=ifupdown,keyfile
no-auto-default=00:a0:d1:ad:18:1a,
[ifupdown]
managed=true
I would be very grateful if anybody could help
Thanks a million!!
