wireless dropping out system preferences freezes

Hi Everybody,

Has anyone had this problem? I will be using the internet over WIFI and then all of a sudden it will drop out it will still show as connected but it just wont work. If I then go and try and open system preferences they will just bounce in the toolbar and not open. I cannot force quit it, if i do then then that window will freeze as well, but i can still work on all other open windows. The only way i know how to fix it is to crash my mac but this occurs once a day atleast and as you can imagine is incredibly frustrating! I recently reinstalled lion to get rid of another bug that wouldnt go away. but if possible is there another way round this as that took forever. I have the latest OSX installed and nothing has changed since it started happening and since i am new to mac i really dont know how to go about fixing it. Any ideas?

Cheers.