I/O pin default low.

[pescador]

attached pdf

[richard]

that's a fairly standard sort of high-side switch that I would expect to be ok.

given that pic i/p leakage current is typically 100nA~ish MAX either R4 is not what is depicted
or your code is not as described [bootloader maybe].
you could try a smaller R4

Thats about all i can see

Somehow my program is restarting when I introduce an input.

is a different story, a big heavy load needs a good power supply and adequate filtering
together with a proper layout to prevent noise affecting the logic circuits