we have a Pic 16F728A which we are trying to get working wtih a 16 or 20 MHZ crystal. We use a 5v power supply, brown out reset is off, watchdog timer disabled. With the crystals, we attach 22pf capacitros between crystal and ground, as stated in the manual. The problem is that the pic is unstable when we turn it on! all we are trying to do is turn on an led and keep it on...however the led flashes randomly...we have tried using higher level capacitors (up to 68pf) but it keeps happening.....we have read somewhere that we may have to include a resistor between crystal and pin..is this reccomended? would this fix the problem? why is this problem happening?