Interrupt driven Buffered Serial Input

[skimask]

DISABLE before here
ENABLE after your interrupt subroutine
Jump over your interrupt subroutine with a Goto Main or something
ON interrupt GOTO GestIntrerupts        ' Deal with interrupts
ReadSerial:
   DataRec var byte[5] : DataRec = 0 : PIE1.5 = 1
   While CounterA <= 70 : WEND
   PIE1.5 = 0				' Disable interrupt on USART
   FOR COUNTERB=0 to COUNTERA:SEROUT2 SerWRT,16416,[SerDATA(COUNTERB)]:NEXT COUNTERB
   Goto ReadReadyLoop 
Not really a good idea inside an interrupt subroutine
' Subroutines
Disable				' Don't check for interrupts in this section
getbuf:				' move the next character in buffer to bufchar
index_out = (index_out + 1):IF index_out > (buffer_size-1) Then index_out = 0
bufchar = buffer[index_out]:Return
error:     errflag = 0:CREN = 0:CREN = 1:GoTo display		' Carry on
buffer_error:
errflag.1 = 1:index_in = (index_in - 1) MIN (buffer_size - 1):HSerin [buffer[index_in]]
usart_error:     errflag.0 = 1		' Set the error flag for hardware
Resume					' Return to program
GestIntrerupts:
IF INTCON.2 = 1 then
T0CON.0 = 0:TMR0L = 0:TMR0H = 0:TimeCount = TimeCount + 1:T0CON.0 = 1:INTCON.2 = 0
ELSE COLON isn't needed but IF RCIF = 1 THEN moved to next line is needed : IF RCIF = 1 THEN
IF OERR Then usart_error			' Check for USART errors
index_in = (index_in + 1):IF index_in > (buffer_size-1) Then index_in = 0
IF index_in = index_out Then buffer_error	' Check for buffer overrun
HSerin [buffer[index_in]]:SEROUT2 SerWRT,16416,[buffer(index_in)]:SerData(CounterA)=buffer(index_in)
CounterA = CounterA + 1	    
IF RCIF Then GestIntrerupts   		' Check for another character while we're here 
ENDIF : ENDIF
resume
ENABLE

Where is your main loop?
You're using HSerIn with interrupts. HSerIn will wait for the NEXT character into the USART receive register after the interrupt trips.
Lots of little problems with this code...rework it a bit, straighten it out, actually READ thru it from top to bottom and see how it executes, repost, and we'll work it from there...