"Honey, my PIC ADC pin sagged my peak detector voltage!"

[Darrel Taylor]

Edit: It seems this PIC (16f1828), doesn't disable PORTC weak pullups at initialisation, it should, this from the datasheet...

"All pull-ups are disabled on a Power-on Reset"

however I've just added the explicit line WPUC = 0 & now everything is reading 0 as expected on my Analogue/ ADC pins

Hank,

Weak Pull-ups are disabled at power-up / Reset.
They are turned on by clearing WPUEN (OPTION_REG.7).
All of the WPUx registers are enabled at power-up, so when you clear the WPUEN bit, they all come on unless you specifically disable individual pins WPUC.x.

Does your code change OPTION_REG?