What OS are you using? Windows?
Are you using the latest version IDE? V1.0.1 is the good one. Earlier versions had a problem with the w5100 interface.
You can ping the ethernet shield with that ip?
ping 192.168.1.2
...and you are using this URL?
http://192.168.1.2
...and if you power down the shield it no longer responds to the ping?