Unable to connect to unsecure networks

For some reason my Windows Vista allows me to connect to my secured internet at home but it won't allow me to connect to any unsecure network (ie. hotel or cafe internet). Has anyone else had this problem and how do you fix it? I have checked all the setting and cannot figure out what is preventing me from being able to access unsecure networks.

Make sure your set to "automatically detect settings" for ip address and dns address... If not, that SHOULD fix it; however I have noticed that for some strange reason, my Microsoft experience (with xp and vista) is that SOME computers do not want to get automatic (DHCP) addresses from SOME routers (theres no rhyme or reason to it), when others do! If thats the case, manually entering an ip/subnet/gateway/dns address that works with the network you are connecting to usually lets you in! (If its a public router, like a hotel or hotspot, then good luck guessing the right numbers!)