You could try this:
Click Start,
Click Control Panel,
Double Click Network Connections,
Right click your wireless connection, then click properties,
In the box that says "This connection uses the following items:", click Internet Protocol (TCP/IP), then click the properties button.
Make sure "Obtain an IP address automatically" and "Obtain DNS server address automatically" are selected.
OK your way out of all the boxes and hopefully all will be good after that.