Switching relays using a webserver

Hi everyone.
I’m having a rather strange problem: using a Duemilanove Atmega328 with a ENC28J60 ethernetshield, I want to control some relays.

The relays by itself work fine:

void setup() {
 pinMode(0, OUTPUT);     
}

void loop() {
      digitalWrite(0, LOW);      
      delay(2000);           
      digitalWrite(0, HIGH);
      delay(2000);           
}

However, when I put up my webserver, I seem to loose all control over the relays:

// EtherShield webserver demo
#include "EtherShield.h"

// please modify the following two lines. mac and ip have to be unique
// in your local area network. You can not have the same numbers in
// two devices:
static uint8_t mymac[6] = {0x54,0x55,0x58,0x10,0x00,0x25}; 
 static uint8_t myip[4] = {192,168,1,25};


#define MYWWWPORT 80
#define BUFFER_SIZE 550
static uint8_t buf[BUFFER_SIZE+1];

#define STR_BUFFER_SIZE 22
static char strbuf[STR_BUFFER_SIZE+1];

// The ethernet shield
EtherShield es=EtherShield();

uint16_t print_webpage(uint8_t *buf, byte on_off);
int8_t analyse_cmd(char *str);

uint16_t http200ok(void)
{
  return(es.ES_fill_tcp_data_p(buf,0,PSTR("HTTP/1.0 200 OK\r\nContent-Type: text/html\r\nPragma: no-cache\r\n\r\n")));
}

// prepare the webpage by writing the data to the tcp send buffer
uint16_t print_webpage(uint8_t *buf)
{
  uint16_t plen;
  plen=http200ok();
  plen=es.ES_fill_tcp_data_p(buf,plen,PSTR("<html><head><title>Home control</title></head><body>"));
  plen=es.ES_fill_tcp_data_p(buf,plen,PSTR("Bureau
"));
  plen=es.ES_fill_tcp_data_p(buf,plen,PSTR("<form METHOD=get action=\"\">"));
  plen=es.ES_fill_tcp_data_p(buf,plen,PSTR("<input type=hidden name=bureau value=1>"));
  plen=es.ES_fill_tcp_data_p(buf,plen,PSTR("<input type=submit value=\"On\"></form>"));
  plen=es.ES_fill_tcp_data_p(buf,plen,PSTR("<form METHOD=get action=\"\">"));
  plen=es.ES_fill_tcp_data_p(buf,plen,PSTR("<input type=hidden name=bureau value=0>"));
  plen=es.ES_fill_tcp_data_p(buf,plen,PSTR("<input type=submit value=\"Off\"></form>"));
  plen=es.ES_fill_tcp_data_p(buf,plen,PSTR("</body></html>"));
  return(plen);
}

uint8_t find_key_val(char *str,char *key)
{
        uint8_t found=0;
        uint8_t i=0;
        char *kp;
        kp=key;
        while(*str &&  *str!=' ' && found==0){
                if (*str == *kp){
                        kp++;
                        if (*kp == '\0'){
                                str++;
                                kp=key;
                                if (*str == '='){
                                        found=1;
                                }
                        }
                }else{
                        kp=key;
                }
                str++;
        }
        if (found==1){
                // copy the value to a buffer and terminate it with '\0'
                while(*str &&  *str!=' ' && *str!='&' && i<STR_BUFFER_SIZE){
                        strbuf[i]=*str;
                        i++;
                        str++;
                }
                strbuf[i]='\0';
        }
        return(found);
}

int8_t analyse_cmd(char *str)
{
        int8_t r=-1;
     
        if (find_key_val(str,"cmd")){
                if (*strbuf < 0x3a && *strbuf > 0x2f){
                        // is a ASCII number, return it
                        r=(*strbuf-0x30);
                }
        }
        return r;
}

void setup(){
  
  Serial.begin(9600);
  
  pinMode(0, OUTPUT);     
  
  /* Disable SD card */
  pinMode(4, OUTPUT);
  digitalWrite(4, HIGH);
  
  // Initialise SPI interface
  es.ES_enc28j60SpiInit();

  // initialize enc28j60
  es.ES_enc28j60Init(mymac);

  // init the ethernet/ip layer:
  es.ES_init_ip_arp_udp_tcp(mymac,myip, MYWWWPORT);
  
   Serial.println("Setup ready.");
}

void loop(){
  uint16_t plen, dat_p;
  int8_t cmd;

  while(1) {
       
    // read packet, handle ping and wait for a tcp packet:
    dat_p=es.ES_packetloop_icmp_tcp(buf,es.ES_enc28j60PacketReceive(BUFFER_SIZE, buf));

    cmd=analyse_cmd((char *)&(buf[dat_p+5]));
        
    /* dat_p will be unequal to zero if there is a valid 
     * http get */
    if(dat_p==0){
      // no http request
      continue;
    }
    // tcp port 80 begin
    if (strncmp("GET ",(char *)&(buf[dat_p]),4)!=0){
      // head, post and other methods:
      dat_p=http200ok();
      dat_p=es.ES_fill_tcp_data_p(buf,dat_p,PSTR("<h1>200 OK</h1>"));
      goto SENDTCP;
    }  
    
    // just one web page in the "root directory" of the web server
    if (strncmp("/ ",(char *)&(buf[dat_p+4]),2)==0){
      dat_p=print_webpage(buf);
      goto SENDTCP;
    }
      
// Nothing happens here...
// Same without the "if"
// The code however is reachable

    if (cmd==1){
       digitalWrite(1, LOW);
    }
    else if (cmd==0){
      digitalWrite(0, HIGH);
    }
Serial.println("this code is reachable!!!");

SENDTCP:
    es.ES_www_server_reply(buf,dat_p); // send web page data
    // tcp port 80 end

  }

}

Any ideas?

Thanks

  Serial.begin(9600);
  
  pinMode(0, OUTPUT);

Perhaps you failed to notice that pins 0 and 1 have alternate labels...