I had similar errors after updating the C18 C compiler. It altered my path statement, so
MPLAB was using a newer version of the MPASM assembler that wasn't compatible with
the version of PBP I was using.

What was really odd was that in MPLAB, when the MPASM assembler window popped-up,
it showed it was using the older version of MPASM, but examining the .LST file showed it
was actually using the newer version of MPASM in my C18 directory.

I fixed it by editing my path statement placing PBP & MPLAB before the C18 directory entry.

Once it started using the older version of MPASM, the problem was cured.