ethernetshield and serial communication

Hello,

I just bought an arduino ethernet shield, and i am new to this thing.

I tried the webserver example and it most of the time works. The arduino resets several times before it works but after a few resets (4 - 10) it works.
I also tried the webclient, same problem.

For some reason serial communication is almost impossible. Because of the amounts of resets the thing does my pc doesn't understand it anymore and stops recognizing the comport. I have to unplug the usb and then plug the usb and then try again. Also programming the arduino with the network cable plugged in doesn't work (pligging in the network cable does always a reset).

Also when opening a serial monitor, the arduino resets, then the ethernet shield reserts the arduino several times and the connection will be lost.

Is this normal behavior? I know that it is normal that the arduino resets when you connect to serial. But is it also normal that the ethernet shield resets several times?
What can cause this?

Thanks in advance.

I have this shield : http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=250851624111&ssPageName=STRK:MEWNX:IT

Ethernet shield and serial communication fails. If I had to guess, you are using a Linux compiler. Is that correct? If so:
http://arduino.cc/forum/index.php/topic,67519.0.html

Sorry i didn't include that information in the thread, didn't know it was needed but:

Operating system: Windows 7
Arduino Duemilanove ATmega328p

So, i don't think this will help.