Garmin map update fails

[Perik Omo]

I have "lifetime" maps for my Garmin Nuvi but I cannot update the maps. I have Garmin Express on my macbook pro but the update fails after a few secs and says that I must delete all the temporary files from the last update, thing is I have no idea where these temporary files are on the mac or what they are called. I've emptied the trash and restarted the machine a couple of times but the problem persists. Anybody now where these "temporary" files are and what they are called?