I had a lot of linker problems with IAR 5.50 when using file portmacro.s90 as supplied. I sugest to modify the interrupt vector definition :

Original :

ASEG
ORGTIMER1_COMPA_vect; Vector address
jmpSIG_OUTPUT_COMPARE1A; ISR


new :

COMMON INTVEC:CODE:ROOT(1)
ORGTIMER1_COMPA_vect; Vector address
jmpSIG_OUTPUT_COMPARE1A; ISR