> > 1. I have noticed that if I touch the top of the ic with my finger
> > the usb connection to my computer breaks. Is this normal?
> 
> Not likely... Usually that means a digital IO line has been left
> floating somewhere. Check that every single digital input, including
> ones going to the PC, is definitively held in a valid state.
> 
> One example of this would be IO lines on your PIC that aren't being
> connected to them. Either make sure they are set as outputs, or tie them
> to V+ or ground through a 10k resistor.

This is about the inputs, I have seen in the datasheet that after power-on
all the TRIS registers are set as inputs. So what is the recommended
practice, I suspect unused pins should be left as inputs, isn't that why
they are reset to inputs in the first place?

Secondly, what is the recommended procedure with unused pins, to
leave them alone, or to connect them to gnd or something, don't they
have a week pull up/down internally anyway?

And why would touching an input would have any effect on the pic,
unless there is some firmware which is monitoring these pins, which
there isn't, I can't see why this could possibly be the reason, and 
maybe it is a capacitance issue,  i.e normal  expected behaviour?
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