Strange problem with the VPBDIV register

#include <LPC21XX.h>
#include <stdio.h>

#define OSC_CLOCK_FREQ 14745600
#define CR     0x0D

void
UARTInitialize(unsigned int baud)
{
  U0LCR = 0x83; /* 8 bit, 1 stop bit, no parity, enable DLAB */
  U0DLL = 192;	/* 9600 bps @ Peripheral Clock = 2 * 14745600 MHz */
  U0DLM = 0;
  U0LCR &= ~0x80; /* Disable DLAB */
  PINSEL0 = (PINSEL0 & ~0xF) | 0x5;
  U0FCR = 1;
}

unsigned int
cClkFreq(void)
{
  return (OSC_CLOCK_FREQ * (PLLCON & 1 ? (PLLCFG & 0x1F) + 1 : 1));
}

unsigned int
pClkFreq(void)
{
  unsigned int divider=0;
  switch (VPBDIV & 3)
    {
      case 0:
        divider = 4;
        break;
      case 1:
        divider = 1;
        break;
      case 2:
        divider = 2;
        break;
    }
  return cClkFreq() / divider;
}

int putchar(int ch)
{
  if (ch == '\n')  {
    while (!(U0LSR & 0x20));
    U0THR = CR;
  }
  while (!(U0LSR & 0x20));
  return (U0THR = ch);
}

int main (void) {
   UARTInitialize(9600);

   printf("Processsor Clock %d\n", cClkFreq());
   printf("Peripheral Clock %d\n", pClkFreq());
   printf("Peripheral Clock %d\n", pClkFreq());
   printf("Peripheral Clock %d\n", pClkFreq());

  while (1) ;
  return 0;
}