This is a really weird problem. I have a circuit that has a serial output to monitor temperatures and functions and noticed the display is going totally wonky. Random character from hell actually, locks up, resets etc. After some time I have narrowed the problem to the oscillator section. The oscillator I'm using is a 4.000MHz crystal and a pair of 22pF capacitors. This is the really strange part, if I remove the capacitors from the circuit the board works prefect. If I leave on cap in it still works perfect. The traces between the PIC and the crystal are extremely short, the crystal is right beside the micro. I don't understand how this can be happening. Anyone have any ideas what might be causing this? If I install a resonator is works fine as well.