Can you get on any other wireless network with the Lenovo, or are other networks visible? Could wireless be turned off on the Lenovo?
If its not turned off then on the router try setting the security options to WPA-PSK [TKIP] + WPA2-PSK [AES] and the Mode option Up to 300 Mbps, then apply/save. Try again and see if you can connect. If not, then try resetting the router and see if anything changes.