RL-ARM control got stucked in

I am trying to interface RS232,CAN and Ethernet to ARM7 using RL-ARM Library. I am using MCB2300 Evaluation Board for this. I am referring EasyWeb example program for interfacing Ethernet. First I interfaced RS232 and CAN using RL-ARM to ARM7. It worked perfectly. Then I tried to interface Ethernet along with that. Here the problem rises. Below is the overall program in which I interfaced all the three serial communication drivers. Only Ethernet task is running. Control is not moving to other tasks. I tried by changing priority of all tasks. I didn't get the expected result.

#include <RTL.h>
#include <LPC23xx.h>
#include "RTX_CAN.h"
#include "LCD.h"
#include <stdio.h>
#include "Net_Config.h"
#include <stdlib.h>
#include <string.h>
#define extern

__task void task_init     (void);
__task void task_send_CAN (void);
__task void task_rece_CAN (void);
__task void task_disp     (void);
__task void task_srec     (void); //serial send
__task void task_ssend    (void); //serial receive
__task void task_ethernet (void);

U32 Tx_val = 0, Rx_val = 0;

char hex_chars[16] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};

typedef struct {
   U32 v;
} mboxx;

os_mbx_declare (MsgBox,4);
_declare_box (mpool,sizeof(mboxx),16);



__task void task_init (void)  {
  os_tsk_create (task_srec, 1);
  os_tsk_create (task_ssend, 1);
  os_tsk_create (task_send_CAN, 1);
  os_tsk_create (task_rece_CAN, 1);
  os_tsk_create (task_disp    , 1);
  os_tsk_create (task_ethernet, 1);
  os_tsk_delete_self();
}


__task void task_disp (void)  {
  for (;;)  {
    Out_Val ();
    os_dly_wait (10);
  }
}


__task void task_srec (void)  {
    mboxx *rptr;
  for (;;) {
    os_mbx_wait (MsgBox, (void **)&rptr, 0xffff);
    printf ("\nAD Value:%d\n",rptr->v);
    _free_box (mpool, rptr);
  }
}

__task void task_ssend (void)
{
  mboxx *mptr;
  os_mbx_init (MsgBox, sizeof(MsgBox));
  os_dly_wait (5);
  mptr = _alloc_box (mpool);
  for(;;)
  {
  mptr->v=0x05;
  os_mbx_send (MsgBox, mptr, 0xffff);
  IOSET1 = 0x10000;
  os_dly_wait (100);
  }
}

__task void task_ethernet (void)
{
  TCPLowLevelInit();
  HTTPStatus = 0;
  TCPLocalPort = TCP_PORT_HTTP;
  for(;;)
  {
   if (!(SocketStatus & SOCK_ACTIVE)) TCPPassiveOpen();
   DoNetworkStuff();
   os_tsk_prio_self(5);

  }
}

int main (void)  {
  serial_init ();
  In_Init  ();
  Out_Init ();

  _init_box (mpool, sizeof(mpool),sizeof(mboxx));
  os_sys_init (task_init);

}


void HTTPServer(void)
  {
           if (SocketStatus & SOCK_CONNECTED)
             {
                  if (SocketStatus & SOCK_DATA_AVAILABLE)
                           TCPReleaseRxBuffer();
                  if (SocketStatus & SOCK_TX_BUF_RELEASED)
                   {
                       if (!(HTTPStatus & HTTP_SEND_PAGE))
                        {
                            HTTPBytesToSend = sizeof(WebSide) - 1;
                            PWebSide = (unsigned char *)WebSide;
                        }
                       if (HTTPBytesToSend > MAX_TCP_TX_DATA_SIZE)
                        {
                          if (!(HTTPStatus & HTTP_SEND_PAGE))
                           {
                              memcpy(TCP_TX_BUF, GetResponse, sizeof(GetResponse) - 1);
                              memcpy(TCP_TX_BUF + sizeof(GetResponse) - 1, PWebSide, MAX_TCP_TX_DATA_SIZE - sizeof(GetResponse) + 1);
                              HTTPBytesToSend -= MAX_TCP_TX_DATA_SIZE - sizeof(GetResponse) + 1;
                              PWebSide += MAX_TCP_TX_DATA_SIZE - sizeof(GetResponse) + 1;
                           }
                          else
                           {
                              memcpy(TCP_TX_BUF, PWebSide, MAX_TCP_TX_DATA_SIZE);
                              HTTPBytesToSend -= MAX_TCP_TX_DATA_SIZE;
                              PWebSide += MAX_TCP_TX_DATA_SIZE;
                           }
                           TCPTxDataCount = MAX_TCP_TX_DATA_SIZE;
                           InsertDynamicValues();
                           TCPTransmitTxBuffer();}
                         else if (HTTPBytesToSend)
                         {
                           memcpy(TCP_TX_BUF, PWebSide, HTTPBytesToSend);
                           TCPTxDataCount = HTTPBytesToSend;
                           InsertDynamicValues();
                           TCPTransmitTxBuffer();
                           TCPClose();
                           HTTPBytesToSend = 0;
                         }
                         HTTPStatus |= HTTP_SEND_PAGE;
                   }
              }
              else
               HTTPStatus &= ~HTTP_SEND_PAGE;
   }

 void InsertDynamicValues(void)
  {
    unsigned char *Key;
    char NewKey[5];
    unsigned int i;
    unsigned int vv,vv1;
    if (TCPTxDataCount < 4) return;
    Key = TCP_TX_BUF;
    for (i = 0; i < (TCPTxDataCount - 3); i++)
     {
       if (*Key == 'A')
         if (*(Key + 1) == 'D')
           if (*(Key + 3) == '%')
              switch (*(Key + 2))
                {
                  case '7' :
                  {
                     vv=In_Get();
                     sprintf(NewKey, "%3u", vv);
                     memcpy(Key, NewKey, 3);
                     break;
                  }
                  case 'A' :
                  {
                         vv1=In_Get();
                         sprintf(NewKey, "%3u", vv1);
                         memcpy(Key, NewKey, 3);
                         break;
                  }
                }
       Key++;
      }
  }

Actually I am new to RTOS. I don't know where I am making mistake. Anybody please point out the mistake I made.
Note: I removed some functions and two tasks(CAN send and CAN receive). Those are working good.