every 2 seconds zone alarm pop up an alert that it blocks internet acess to my computer (tcp port 445), i try to follow thei explanation to this happening , the windows simple sharing thing, but this remains the same, so i just turn off the alerts.... but in your opinion this are serious alerts or just normal internet trafic?

Pst exctly what the pop up says.
Also, as long as they are blocked it is working OK, but the next step would be to examine your security logs in ZA looking for patterns, but honestly, port 445 scans and others are common. As are many other ports. I'd turn off the pop up windows and it will block them silently, but make very certain you have your ZA configured correctly, in that it has to ask for permission and that you have NOTHING checked yes to a server, unless you are running a server.
Go to www.pcflank.com and www.grc.com and www.broadbandreports.com and run their security scans to know more about your PC defenses.