Dspic and hangs when running on low frequence

Hi!
I have a DSPIC 30F6014 and have a problem.
It is used for sampling data at a frequence of 3,3 khz the external
cristall of 32768 devided with 10.
The DSPIC are running on 6MHZ external cristall and PLL 4 times, wich
gives 24MHZ, and is trigged to start 3,3 khz.
Using this speed everything works perfektly.
But during standby mode i divide 32768 to get 51,2 HZ, to save power.
Becouse of this the intstrument approx once a day hang.
Before that recieving huge amount of Ochilator fail trap and even
adress errors.

Increasing the standby freq to approx 500 hz solves the problem but
drains my battery.
Does anyone have a clue why this happens?

/Martin

"Source Code"
	T1IE =3D 0;               // Interrupt Disable
	if(IsTimerLowPower())
	{
		if(bFast)
		{
			if(g_LowSpeed && !IsTrigged())
				PR1 =3D (PR1_LOW-1);  // 1092,267 Hz from 32768 Hz external
			else
			    PR1 =3D (PR1_ORG-1);  // 3276,8 Hz from 32768 Hz external change
here for different clock =E4ndra spleep och timer grejer ocks=E5 f=F6r det
ska funka
		}
		else
		    PR1 =3D (PR1_SLOW-1);  // Timer ticks to generate 51,2 Hz from
32768 Hz external
	}
	else
	{
		if(bFast)
		{
			if(g_LowSpeed && !IsTrigged())
			    PR1 =3D ((MCK*PR1_LOW)/(32768*4)); // 1092,267 Hz from MCK
internal
			else
			    PR1 =3D ((MCK*PR1_ORG)/(32768*4)); // 3276,8 Hz from MCK internal
		}
		else
		{	// Warning!!! this timer goes 2x, else the PR1 value would be
greater than 65535
		    PR1 =3D (((MCK/8)*PR1_SLOW)/32768); // Timer ticks to generate
102,4 Hz from MCK internal
		}
	}
	if(bFast)
	{
		if(g_LowSpeed && !IsTrigged())
			g_nTimerTickComp =3D PR1_SLOW/PR1_LOW;
		else
			g_nTimerTickComp =3D PR1_SLOW/PR1_ORG;
	}
    TMR1 =3D TMR1 % PR1;      // Reset Timer1 to lower than PR1
    T1IE =3D 1;               // Interrupt Enable