Hi all, first post here. I hope this is the right place. I had ethernet shield installed on an Arduino Mega, and wanted to add an LCD (2x16 for what it matters). The LCD installed directly "on top" on the Ethernet Shield does not work for geometric reasons (the ethernet connector external plate touches the connectors on the LCD), and inverting LCD and Ethernet shield position obviously is not a great choice since you cannot see the LCD behind the ethernet shield... ;) Then i connected the LCD with some wires to pins 42-44-46-48-50-52 of the Mega, so I can put the LCD where I want. The LCD starts ok but after Ethernet.begin a number of strange characters appear on the LCD, and my LCD.print did not work anymore. I moved the LCD on upper right digital pins (23-25-27-29-31-33) and it works correctly. I suppose that's something related to the Ethernet shield that initializes and uses some pin in the 42-52 range, perhaps for compatibility with older boards? I know that to get older Ethernet shield working on the Mega there was some trick involving using those pins, but I just started working with the Arduino and my knowledge is very poor.
Hope that this helps someone with my problem, or maybe that this helps fixing the problem.
I can give further details if required.
Thank you all for great community