Hi Michael. I use the 16C72A frequently. Now using 16F73 as a substitute. It is on a board that uses portc only as outputs and I never had a problem using any or all of them. This was at the top of my last program. Try this at the top of your program and see what happens:
ADCON1 = 7 'set inputs to digital
@ DEVICE WDT_ON, BOD_ON, PWRT_ON, PROTECT_ON
TRISA = %00110010 'RA1,4,5 INPUTS, REST OUTPUTS
TRISB = %11111101 'RB1 OUTPUT, REST INPUTS
TRISC = %00000000 'ALL OUTPUTS