Problems with my AIRPORT connection

Hi there i have a MACBOOK PRO 10.6.8 and recently i been having problem with my airport connection. Airport is able to see the networks available out there but when i do try to enter my password on my newwork it tries and sometimes it says CONNECTION TIME UT or sometimes it says INVALID PASSSWORD. i tried everything that are suggested here in forum but i cant seem to fix the problem. So the only way i am cinnected right now is with ethernet cable. When i try to do the scanning of Airport utilitiy devices it says that it was unable to find any airport wireless devices. i have done also turning off and on the airport and then selecting my network but still same reaction
Thanks for your time again guys

i'm having a similar problem. Our Macs can often connect to a wireless router, but not to that router's internet. We get full bars, but no internet. I can't find any reason why it connects sometimes, and sometimes it doesn't. Any advice?

What has always worked for me is encrypt using WPA2 take the router off of auto channel select one manually and connect using DHCP.