Let's first check your IP settings and see if you can ping google.com
In Windows 7 click the start orb
and type in the search box cmd hit enter
in command line type:
what are the results for your wireless connection?
Also does this only happen when in wireless? If you can directly connect to the router/modem to see if you can get internet that way..
Let's also do a simple ping to google.com just type:
what are the results?