network connection problems! help!!

i keep getting the error message "a connection timeout occurred" with my mac book pro on a certain network that need to connect to on a daily basis. its got a wpa2 personal password and the problem started when i upgraded to OS 10.7

i have no problem connecting with any other network... if anyone can help me that would be great! i know if i go to the genius bar they are going to just say "talk to your service provider because there is nothing wrong with your hardware"... ive talked to the service provider and they are absolutely no help.

any advice would be awesome...

thank you,
Kevin

What is this 'certain network'?

Do you have access to the router settings? or are you able to talk to the administrator of the router?