Yesterday, i got my new Arduino Ethernet shield working with the Web Server code and I was running it off of USB power just fine. Now however, it does not power on. It works with only the arduino uno plugged to usb but when the ethernet shield is stacked it does not work. The power light goes on put fades away after about a second. When this is happening the chip that says 509Z (Near USB on the main board) gets very hot.
Any Help would be greatly appreciated. 
What have you done with the arduino and ethernet shield between the time it worked and and the time it didn't work?
I haven't done anything unusual i first plugged it in with USB and when i saw that that did not work i tried batteries and a wall adapter.
Trevor
That chip that's getting hot is the fuse. If it gets hot and the power light goes out it means you are drawing too much current off the USB. It is made of a doped polymer that has a high positive temperature coefficient (becomes less conductive as it gets hot).
Pull the Ethernet shield off and carefully inspect both boards very carefully with light and a magnifying glass. Look for a small short, like ball or flash of solder, or even a little bit of trimmed wire. Brush both sides of each board with a medium stiff brush (old tooth brush works well) and blow them of with compressed air if you can.