Olimex STM32-P103 and Keil uVision 4.0 Lockup issue

Trying to get a simple flashing LED application running on the target board and can compile - load and single step through code (F11) no problem, LED flashes.

If I try to jump over any statement / method using F10 the program freezes and looks like its in STM32F10x.s

Default_Handler PROC

EXPORT WWDG_IRQHandler [WEAK]
. .
. .
EXTI15_10_IRQHandler
RTCAlarm_IRQHandler
USBWakeUp_IRQHandler

=====> (looks to break here) B .

main is as follows...

int main(void)
{ #ifdef DEBUG debug();
#endif

stm32_Init();

while (1) { /* Turn on LD1 */ GPIO_SetBits(GPIO_LED, GPIO_Pin_12); /* Insert delay */ Delay(HALF_SECOND);

/* Turn off LD2 and LD3 */ GPIO_ResetBits(GPIO_LED, GPIO_Pin_12); /* Insert delay */ Delay(HALF_SECOND);

}
}

Tried everything I can think off so any ideas / help appreciated.

Thanks in advance..