> Yes, that would do it.

Changed the PIC - same story.


> Dumb question, is this particular pic specified to run at this low voltage
> and at this xtal speed?

Oh bugger. I had naively taken it for granted that the quoted' wide
operating range of 2.0 to 5.5V' was for all operating speeds... and looking
at the datasheet it seems this isn't the case..

According to the datasheet, I'll need at least 4.5V. I think you may have
hit the nail on the head!

Kieran