Issue with TIMER1_A0_VECTOR on msp430f5528 trying to create PWM on TA1.0

I'm having a issues with the ISR function being called.    I'm using examples based from this document slaa513.pdf. 

I put the timer into continous mode (MC_2) and enable the interrupt (TAIE) and trying to use SMCLK (TASSEL_2)

The problem is it freezes, sometimes it goes into the the interrupt routine other times it does not. 

if I use TASSEL_1 it will work for a while and then freeze.  I have tried setting up the SMCLK it a couple ways but it doesn't see to help.  And if I create a PWM using MC_1 on TA1.1 to create a PWM it works fine using SMCLK.   

Is there something simple I'm missing here?

Code pasted below.. Note how I'm trying to vary the duty cycle using the servo1_value var in a simple loop.

#include <msp430f5528.h>

// SERVO 1 connected to P1.7/TA1.0

#define     PWM_SERVO1_BIT BIT7 //P1.7

#define     PWM_SERVO1_DIR P1DIR // Each Servo uses the different DIR,SEL,OUT

#define     PWM_SERVO1_OUT P1OUT

#define     PWM_SERVO1_SEL P1SEL

#define PWM_SERVO1_TxCCR TA1CCR0 //Timer A1 TA1.0

#define PWM_SERVO1_TxCCTL TA1CCTL0

#define PWM_SERVO_TIMER_CONTROL TA1CTL

#define PWM_SERVO_PWM_PERIOD TA1CCR0

#define PWM_SERVO_MIN   250 // old values

#define PWM_SERVO_MAX   500

#define PWM_SERVO_PERIOD   500

// LED defines for bits and outputs.

#define     LED_RED_BIT BIT7

#define     LED_BLUE_BIT BIT6

#define     LEDS_DIR P6DIR

#define     LEDS_OUT P6OUT

// LED ON/OFF Commands.

#define LED_RED_OFF LEDS_OUT &= ~LED_RED_BIT

#define LED_BLUE_OFF LEDS_OUT &= ~LED_BLUE_BIT

#define LED_RED_ON LEDS_OUT |= LED_RED_BIT

#define LED_BLUE_ON LEDS_OUT |= LED_BLUE_BIT

#define LED_RED_CYCLE LEDS_OUT ^= LED_RED_BIT

#define LED_BLUE_CYCLE LEDS_OUT ^= LED_BLUE_BIT

unsigned int servo1_value = PWM_SERVO_MIN;

void main(void) {

WDTCTL = WDTPW+WDTHOLD; // Stop that silly watchdog timer

// init the ports for setting up the LEDS

LEDS_DIR |= LED_RED_BIT + LED_BLUE_BIT ;  // Set LEDS to output direction

LED_RED_OFF; // start with LEDS OFF

LED_BLUE_OFF; // start with LEDS OFF

PWM_SERVO1_DIR |= PWM_SERVO1_BIT; // setup output direction

PWM_SERVO1_SEL |= PWM_SERVO1_BIT;  // set timer to update this output

PWM_SERVO1_TxCCTL = OUTMOD_4 + CCIE; // enable interrupt

PWM_SERVO_TIMER_CONTROL = TASSEL_2 + MC_2  + TAIE;  // set SMCLK, continous mode, and interrupt enable.

__bis_SR_register(GIE); // enable interrupts

int pos = 0;

int i = 0;

while(1) {

     pos = 240;

     for(i=0;i<=25;i++) {

          pos = pos + 10; // increment for testing purposes

          servo1_value = pos;  // update the duty cycle for the ISR function below

          __delay_cycles(100000); // delay between PWM duty cycle changes.

          LED_BLUE_CYCLE;

     }

}

}

#pragma vector=TIMER1_A0_VECTOR

__interrupt void TIMER1_A0_VECTOR_ISR(void) {

     LED_RED_CYCLE;

         if(TA1CCTL0 & CCI) // If output currently high

         {

              TA1CCR0 += servo1_value; // PWM high  ( this value plus the "else" value needs to equal pwm period.

         } else {

              TA1CCR0 += PWM_SERVO_PERIOD - servo1_value; // PWM low

         }

}