error 65: access violation : no 'execute/read' permission

hello,

i am using the following code to generate a delay of 200ms.

while(tfcount <= 16666)
{
	if (TF1 == 1)
	{
		tfcount++;
		TF1 = 0;
	}
}

im using the Timer 1 as a baud rate generator and it overflows every 12 us. the problem is that when i simulate the code using microvision 3 ,as soon as the while condition becomes false, instaed of continuing down the code, it gives the following error :

*** error 65: access violation at C:0x000B : no 'execute/read' permission

can u please help and tell me how to avoid this.

thanks
saad