Not sure it's got anything to do with your problem but flipping INTCON.5 does not start/stop TMR0 - it enables/disables the interrupt.
Code:
  Timer0_Count:
    
    INTCON.5 = 0                 ' STOP TIMER   <----- No it doesn't
   T0Count1 = T0Count1 + 1      ' inc counter on interupt flag
    TMR0H = $63               ' preset Timer 0 to a 10ms timer
    TMR0L = $C0                              
    INTCON.5 = 1                 ' START TIMER       <------ No it doesn't
@ INT_RETURN
    RETURN
Also, verify that your oscillator is actually running at the expected frequency. A simple LED blinking at 10Hz will tell you if it's off bu a factor of 2.

/Henrik.