Palliser,
Thanks for the heads up, I tried the code though and it has the same problem as the other code I have tried.
I guess at this point I'll attempt to reach out to Jinbuhm Kim and see if he has an idea what is going on. It seems like too many requests to the RX buffer of the W5200 is triggering a condition where it doesn't respond to any more requests. Since all the TCP/IP stack is contained within the W5200 chip it doesn't seem like this is an Arduino problem per se and may be a bug in the W5200 itself.
WIORE, have you been able to try any of the code? Are you still having the same problem? If so, we have a documented issue we can go to WIZnet and see if there is a fix or at least get them to acknowledge the problem.