CCS/MSP430FR2355: code running off in limbo?

Tool/software: Code Composer Studio

Hello...

I have code where I do some clock, gpio and uart set up functions then a while(1) loop.  I have one rx/tx ISR active.  I frequently am finding that my code is somehow resetting....If I place one breakpoint before the while loop I run to it then hit run again and after a short period the code will circle out of the while loop and break at that point.....If I remove the TXIE in INITUART I no longer have the issue.  I am convinced that somehow one of my pointers is running away and causing grief....Can anyone see anything glaring about how I may be poorly handling pointers to cause grief?  In particular the pTx..... 

#include <msp430.h>
#include <string.h>
#include <stdint.h>
#include "rc.h"
#include "LPRSradio.h"

volatile char *pRx;
char incoming[20];
const char *pTx;
const char *configCmdAck[3] = {r_RSSIon, r_bandSet, r_USAFCC};
const char *testack = "ACK";
uint8_t i = 0;
boolean tx = T;
int k;
unsigned int r;
boolean redflag = F;

int main(void)

{
    WDTCTL = WDTPW | WDTHOLD;   // stop watchdog timer

    IOconfig;
    initClockTo16MHz();
    initUART();
    pRx = incoming;
    pTx = configCmdAck[0];
    __bis_SR_register(LPM3_bits + GIE); //go to sleep: LPM3
    while (i<3)
    {
        __bis_SR_register(LPM3_bits + GIE); //go to sleep: LPM3
        if (tx) {
            pTx++;
        }
        else {
            if (!strncmp(incoming, configCmdAck[i], strlen(configCmdAck[i])))
            {
                pTx = testack;
                i++;
                redflag = T;
            }
            pRx++;  //see note below...Do not put at end of loop!
            if (redflag) {
//                redflag = F;
/*URGENT: Setting UCTXIFG must be the last line of code. If set earlier we will go into ISR, come out and process the next line of code
 * before going back into ISR because TXIFG will get set because of TXBUF going empty...This unfortunate event will promote a double character instance.
 * redflag will alert us that we want to go back into ISR...hence prepare everything, create redflag then use it at very end of if statement to generate ISR
 * such that when we return we will move to next line of code (ie LPM3 sleep), then TXIFG will wake us at beginning again.
*/
                UCA1IFG |= UCTXIFG;
            }
        }
    }
    UCA1IE &= ~UCTXIE;
    __bis_SR_register(LPM3_bits + GIE);
}


#pragma vector=USCI_A1_VECTOR
__interrupt void M(void)
{
    switch(__even_in_range(UCA1IV, USCI_UART_UCTXCPTIFG))
    {
      case USCI_NONE: break;
      case USCI_UART_UCRXIFG:
          tx = F;
          *pRx = UCA1RXBUF;
          __bic_SR_register_on_exit(LPM3_bits);
          break;
      case USCI_UART_UCTXIFG:
          tx = T;
          if (*pTx != '\0')
              UCA1TXBUF = *pTx;
          else {
              if (redflag) {
                  redflag = F;
                  pRx = incoming;
                  pTx = configCmdAck[i];
                  for (r = 0; r<2000; r++); //2000 minimum
                  UCA1TXBUF = *pTx;
              }
          }
          __bic_SR_register_on_exit(LPM3_bits);
          break;
      case USCI_UART_UCSTTIFG: break;
      case USCI_UART_UCTXCPTIFG: break;
    }
}