Alfa Romeo 147 starting computer fault? !!

Hi, Can anyone help me regarding my alfa, recently I have been having random errors messages on dash screen only for them not be valid.i.e. side light showing out when ok abs problems again no problem, but recently having problems starting up, turning over but no response no lights on dash , then it does start only to cut out. I finally rang AA who came and reset car computer and said no codes have come up to say where if even ther is a problem!. That was Sunday and tonight playing up again when starting. Could it be computer on way out or is something triggering it to go off. HELP !!!!!!!! Jon