I recently got a Raspberry Pi, but I've been having trouble getting a working internet connection.
At the moment, the pi will connect, and I'll be able to access the internet for about 15 seconds until it suddenly disconnects (it disappears from the list of DHCP devices on my router). I then have to use
sudo /etc/init.d/networking restart to reconnect, which either causes the graphics to freeze or lets the Pi access the internet for another 15 seconds or so. When the GUI (startx) isn't running, and I'm just using
ping 184.108.40.206 the connection doesn't seem to drop.
It's running Raspbian, the power cable is 5V and 0.7A and the eth0 interface is using DHCP. I can provide any other information which might help to diagnose this problem.