Lpc2000

I use a Olimex LPC2214 board and are having some problems. 
When I run this code (see below) I have a few pins that don't "act
normal". When messuring on a working pin I see a square wave with a
duty cycle of ca. 20% and an amplitude of 3.3 V. When I messure on ex.
P0.2 I have the same duty cycle ratio but the voltage is only 200mV.
The defective pins are: P0.2, P0.3, P0.20, P0.27, P0.28 and P0.29. 

I have used the Timers, RTC and on-chip other perf. with no trouble...

Code:

int main(void)
{
	pll_init();
	GPIO0_IODIR |= 0xffffffff;
	GPIO0_IOSET = 0xffffffff;
	while(1)
	{
		GPIO0_IOSET = 0xffffffff;
		GPIO0_IOCLR = 0xffffffff;
	}
}

Regards Jens Alsig