Vista - Have an internet connection, can't access any websites

>I just got a new Toshiba laptop, I am traveling with it in Mexico while
> working. I have intermitent problems with the internet connections. I
> will
> connect to the wireless router at an internet cafe and it will show that I
> have an excellent connection, but I cannot access any websites. When I
> select diagnose problem, it comes back that no problems could be found.
>
> I read posts with problems when the system goes into sleep mode and trying
> to reconnect and having to reboot. I am having this problem when I have
> just
> started the computer. I don't always have this problem, some networks I
> connect to and have no problems accessing the internet. The people at
> the
> internet cafes tell me that they have a lot of problems with people trying
> to
> connect with Vista.
>
> Any ideas, something I can change or look at?