Code entering endless loop

[Blackhawk]

I haven't got a digital version of the circuit diagram, but I can tell you that there is a pull up resistor on MCLR. The input lines will eventually be toggled by another micro so right now they don't have pull down resistors, I suspected residual charge on the pins before so I tried rigging up a pull down resistor (just loosely) and it didn't appear to help, I should try it again properly to make sure however.

EDIT: for reference here is the whole program

' Porta-0 = Y acceleration     $81 then $85
' Porta-1 = X acceleration     $89 then $8D
' Porta-2 = Pressure           $91 then $95
' Portb-0 = Arm input
' Portb-1 = Machdelay input
' Portb-2 = Apogee charge
' Portb-3 = Main charge
' Portb-4 = Buzzer

Symbol  PortB = 6       'PortB is register 6
Symbol  TrisB = $86     'PortB data direction is register hexadecimal 86
symbol  ANSEL = $9B     'Analogue select port
Symbol  ADCON0 = $1F    'Analogue control port 0
Symbol  ADCON1 = $9F    'Analogue control port 1
symbol  ADRESH = $1E    'Analogue result register high
Symbol  ADRESL = $9E    'Analogue result register low
poke ANSEL , $F
poke ADCON0 , $80
poke ADCON1 , $80
Poke TrisB , 0
B5 = 1

start:  poke ADCON0 , $91
        pause 1
        poke ADCON0 , $95
        pause 5
        peek ADRESH,B0
        Peek ADRESL,B1
        W6 = W0
        W0 = W0 - 50
        peek PortB, B2
        B3 = B2 & 1
        B4 = B2 & 2
        if B3 = 1 then beep
        if B4 = 2 then delay
        goto start
        
delay:  B5 = B5 + 2
        high 4
        pause 1000
        low 4
        pause 1000
        high 4
        pause 1000
        low 4
        B4 = 0
        goto start
        
beep:   high 4
        pause 5000
        low 4
        goto armed
        
armed:  poke ADCON0 , $89
        pause 1
        poke ADCON0 , $8D
        pause 5
        peek ADRESH,B6
        Peek ADRESL,B7
        if W3 < 300 then machdelay
        goto armed
        
machdelay:  for B8 = 1 to B5
            pause 5000
            next B8
            goto launched
            
launched:   poke ADCON0 , $91
            pause 1
            poke ADCON0 , $95
            pause 5
            peek ADRESH,B6
            Peek ADRESL,B7
            W6 = W6 + 10
            if W3 < W6 then apogee
            W6 = W3
            goto launched
            
apogee: high 4
        pause 5000
        low 4
        high 2
        pause 5000
        low 2
        goto falling
        
falling:    poke ADCON0 , $91
            pause 1
            poke ADCON0 , $95
            pause 5
            peek ADRESH,B6
            Peek ADRESL,B7
            if W3 > W0 then main
            goto falling
            
main:   high 4
        pause 5000
        low 4
        high 3
        pause 5000
        low 3
        end

Actually just looking back over what I posted, I poke portB to all outputs at the start, could this be causing the problems I'm seeing?