MSP430FR2355: code locking up development board

Part Number: MSP430FR2355

Good morning...

I have an MSP430FR2355 Dev board wired to a CO2 sensor that communicates over I2C.  I am sending commands over the UART from the PC to read and write to the sensor as well as some other commands to do a variety of things.  Main sleeps until a UART command is received then accordingly parses and processes it.  The first command I do after receiving the incoming message is to free dynamic memory and allocate a length of memory per request in incoming message (up to a byte).

I notice that (very randomly) that if I do reads/writes over a length of time (also randomly) that the board bricks and stops operating and I have to power it down and re-power it.  The whole application is triggered by incoming mssgs.....I placed a one second watchdog at the front end of main after a mssg is received and I kick it just before I re-enable the RX on the UART after all the processing is done.  I periodically see the watchdog expire (per an LED).  It seems to come after a lengthy access of commands which is implying to me I am somehow not freeing up dynamic memory or something of that nature.

My code is quite long so I will share the bits I hope are pertinent.  These are all the allocation to memory and the watchdog sections.  

As a final note (I am not too familiar with dynamic memory) I notice when I debug that each time I rcv a UART command and free memory and re-allocate for the incoming message that the pointer doesn't seem to point to the same location but rather an incrementing location each time....Is this an issue??

Thanks

uint8_t *pI2CStream, command, temp;
__vo uint8_t mssgLength = 0, dataToSendUser = 0, noOfNacks = 0;

        if (ISR.UARTmssgRcvdFlag)
        {
            WDTCTL = WDT_ARST_1000;  //main has 1 second to process or else a reset occurs
            TimerCC_Delay(TIMER0, CC_ONE, ONE_SECOND - 2);

            free(pI2CStream);
            applicationUART.pSysCommsA->UCAxIE &= ~UCRXIE;
            TimerCC_Disable(TIMER0, CC_ZERO);
            pI2CStream = malloc(mssgLength);

#pragma vector=USCI_A1_VECTOR
__interrupt void COMM_ISR(void)
{
    switch(__even_in_range(UCA1IV, USCI_UART_UCTXCPTIFG))
    {
      case USCI_NONE: break;
      case USCI_UART_UCRXIFG:
          buffer[mssgLength] = UCA1RXBUF;
          mssgLength++;
          if (monitor == 0)
              TimerCC_Delay(TIMER0, CC_ZERO, ONE_SECOND);

          monitor = 1;
          if (UCA1RXBUF == 0x0D)
          {
              mssgLength--;
              ISR.UARTmssgRcvdFlag = T;
              LPM3_EXIT;
          }
          break;

        if (ISR.I2CComplete)
        {
            /*
             * house-keeping
             *
             */
            dataToSendUser = (*(pI2CStream));
            ISR.I2CComplete = F;
            noOfNacks = 0;
            memset((void *)buffer, 0, sizeof(buffer));
            mssgLength = 0;
            monitor = 0; //re-arm timeout counter
            i2c_cnt = 0;
            WDTCTL = WDTPW | WDTHOLD;   // stop watchdog timer
            applicationUART.pSysCommsA->UCAxIFG &= ~UCRXIFG;
            applicationUART.pSysCommsA->UCAxIE |= UCRXIE;
            if (i2cstate == I2CRESTART)
                Mutex.UART_tx = T;
        }