Simple Timer A DCOCLK

I am using MSP430F2274 with CC2500.

Hi i need my DCOCLK to be calibrated to 1 mhz to do something  during the Timer A interrupt. At the same time i want to be able to print to my "Putty" terminal the output that i want. Am i able to do both of these using just the DCOCLK? I do not have a external crystal and i cant rely on the VLOCLK for timer A as there seems to be a large clock drift. i tried to  print to the putty terminal a message,  "Hello",  but its not working. However it works if i remove the calibrations and Timer A. Pls check my code below.

#include "mrfi.h"
#include "radios/family1/mrfi_spi.h"

void start_slow_timeout()
{
  TACTL|=TACLR; TACCTL0=CCIE; TACTL=TASSEL_2+MC_1;
}

int main(void)
{
  BSP_Init();
 
  P3SEL    |= 0x30;
  UCA0CTL1  = UCSSEL_2;
  UCA0BR0   = 0x41;
  UCA0BR1   = 0x3;
  UCA0MCTL  = UCBRS_2;                    
  UCA0CTL1 &= ~UCSWRST;
    
  if(CALBC1_1MHZ == 0xFF || CALDCO_1MHZ == 0xFF)
  {
    P1OUT |=0x02;
    while(1);
  }
 
  BCSCTL1 = CALBC1_1MHZ;
  DCOCTL = CALDCO_1MHZ;
  BCSCTL2 &= ~ BIT3;         

TACCTL0 = 0;                           // TACCR0 interrupt enabled
  TACCR0 = 50000;
  TACTL = MC_0;                  // SMCLK, count up mode
   start_slow_timeout();
  __bis_SR_register(GIE);
  while(1);
}

void MRFI_RxCompleteISR()
{
}

int count=0; // counter to count to 1 sec and print

#pragma vector=TIMERA0_VECTOR
__interrupt void interrupt_slow_timeout (void)
{
  count++;
  if(count==20)
  {
    char xyz[] = {"Hello         \n\r"};
      TXString(xyz, (sizeof xyz));
   P1OUT^=0x01;
    count=0;
  }
     
     
}