Strange problem with the VPBDIV register

Hi:
I tried the following code:

#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;
}

It is compiled with Keil CARM, and the VPB Clock = CPU Clock / 2
The first printf the peripheral clock prints a wrong value, while the rest are correct.
Apparently, the problem is when the VPBDIV register is read. The first time it reads as zero, while the rest it reads the correct value.

Someone have any idea about this?
Thanks
Daniel