DEFINE LCD_RWREG 0 'defines the port where R/W line is connected to (set to 0 if not used)
DEFINE LCD_RWBIT 0 'defines the pin where R/W line is connected to (set to 0 if not used)
I don't think it's a good idea to set those to 0.
It will end up overwriting bit0 at address 0 in RAM which is normally PBP's R0 system variable.

Try it without those lines.

hth,