I know the following is commented out, but not sure what is going on here:
Code:
'ADCON0 = %11000001
'ADCON1 = %10001110

'trisa = %00001110
'trisb = %11110111
You want to make sure all the analog inputs (ADC and Comparators) are set to digital. Also I think your TRIS directives are backwards (i.e. desired output are inputs and viceversa). Again this is commented out, but you should be defining these things at the beginning.

Not sure what the real problem is, but somehow I think you are having a stack overflow.

Try replacing the "GOsub warning" with "GOto warning"; and "RETURN" with "GOto monitor".