Hi,
Are you sure that it is a 4Mhz and not a 10Mhz crystal?
Do you have the correct capacitors inplace to load the crystal?

Try something like
Code:
TRISC.0 = 0
Main:
  PortC.0 = 1
  Pauseus 1000
  PortC.0 = 0
  Pauseus 1000
Goto Main
What's the frequency of the output signal?

/Henrik.