As i remind thos baby PIC don't have any multiplexed stuff on PORTC so i'll bet on a messy contact or bad breadboard.

i just hope your code is longer than this.. let's say
Code:
ADCON1 = 7
TRISA.0 = 1
TRISB = 0
TRISC = 0
HH VAR BYTE
MM VAR BYTE
SS VAR BYTE
DD VAR BYTE
N VAR BYTE
D VAR BYTE
H VAR BYTE
I VAR BYTE
T VAR BYTE
Z VAR BYTE

High PORTC.4
High PORTC.5
Here:
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