Tom,
The first thing I find myself checking these days is ground - is the
*bleep* board grounded properly (this after 2 weeks of debugging a serial
line only to find that a 2 inch oiece of wire was the solution :( ) Then,
did I remember to plug in the chip/emulator. Then, did I remember to turn
on the PSU :) All the idiotic things - mainly because I've been taught by
that 16c74a that I am a functional idiot :)

After that, in this case, the oscillator bits in the config word - is it
set to XT or whatever is appropriate ? Then an oscilloscope on the OSC2
pin to make sure the clock is working !

Hope it helps some ...

--
Mark Dennehy, B.A., B.A.I.  Email : Mark.Dennehy@cs.tcd.ie
Research Student,
Computer Vision and Robotics Research Group,
Computer Science Dept., Trinity College Dublin