hi,
this has been happening a lot to me. there are a lot of things that you have to look for.
goto properties of the wireless connections>wireless connections tab> advanced>click on "any available network. should be clicked anyway.
if there is enough signal coming to your computer. there are some places where the signal is not so strong, so the computer is not able to log in.
right click the wireless connection icon>properties>Internet Protocol (TCP/IP)>properties>general. check if "obtain ip addess automatically" is clicked. if not then click it.
same for automatic configuration (obtain automatically)
in wireless configuration tab (in the properties). click "let windows cofigure my wireless configuration"
still if there is no connection then in the "wireless connections" (same in the properties, wireless connections tab). goto the icon for the connection, then properties, put in the network key (if you have it) you will definately need it.
apply all the settings, the computer will now make a fresh search. if it still doesnt find anything, then restart and try searching again. it should connect automatically (because in the properties again "wireless connections>connection icon>properties>connections tab>click on the "connect when this network is in range".
this should solve it. :D
if it doesnt. i will try and see what i can do and check my settings here to see if there is anything else i check for.