First thing I do when I'm having trouble is either hook up some Status LEDs or a Serial output to debug the pic. I've had trouble with a program or two..and more than once something was causing a reset. Do you have a compiler so you can add in some debugging code?

I believe i did 22pf with my 20mhz...which is more than required by the datasheet. :/ I'm not seeing anything right off :/
Have you verified the usb cable is providing power and works with another device?