> I unmask the USART receive peripheral interrupt (bsf
>   PIE1, RCIE),

init    ;(setup port A/B I/O, set baud rate to 2400bps,
         ;enable async USART transmit, initialize LCD)

        bsf     PIE1, RCIE              ;unmask USART receive interrupt

If you aren't changing to Bank1, then you're setting bit5 in PIR1
(address 0c), not bit5 in PIE1 (address 8c)

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.