external oscillator

Micro MSP430F5171

At 20 Mhz with its internal clock i have found a lot of instability. Thsi with 2 different boards.

So i decided to put a 24MHz extarnal oscillator in hope this wil fix all. Clock inialization is:

void clock(void)
{
 volatile unsigned long i;

 // Increase Vcore setting to level3 to support fsystem=25MHz
 // NOTE: Change core voltage one level at a time..
 SetVcoreUp (0x01);
 SetVcoreUp (0x02);
 SetVcoreUp (0x03);

  // configure clocks
  UCSCTL1|=DISMOD;             //Disable modulator
  UCSCTL4=0;                           //ACLK=SMCLK=MCLK=XT1
  UCSCTL6|=XT1DRIVE_3;     //Drive strength for 25MHz
  UCSCTL6|=XTS;                     //HF oscillator - 1 or 0 should not be important
  UCSCTL6|=XT1BYPASS;      //XT1 bypass oscillator circuit
  UCSCTL6&=~XT1OFF;          //XT1 enabled

  __delay_cycles(782000);

  // Loop until XT1  fault flag is cleared
    do
    {
      UCSCTL7 &= ~(XT1LFOFFG + XT1HFOFFG+ DCOFFG);
                                                                       // Clear XT1,DCO fault flags
      SFRIFG1 &= ~OFIFG;                          // Clear fault flags
    }while (SFRIFG1&OFIFG);                    // Test oscillator fault flag

}

but it doesn't exit loop, fault flag is always on.

Thanks, Enzo