Ubuntu

Comment 0 for bug 865266

Using the Ubuntu version of arduino-core and avr-gcc makes it impossible to get the example Arduino Webserver working.
Reading from the Socket returns garbled output.

The Arduino forum has found as solution, which works for me:
http://arduino.cc/forum/index.php/topic,68624.msg523739.html#msg523739

I've attached a patch for /usr/share/arduino/libraries/Ethernet/utility/w5100.h