Wireless connection good but cannot connect to the internet

Hi
I am facing wireless internet problem wile surfing internet on my laptop can you help me ? In my college i access inter for surfing and accessing information (some time i download also). but from last 2 days i am not able to connect to internet.

I am also facing same problem, i am using linksys router but from last two weeks i am not able to connect my laptop through wifi. I don't know whats the Is there any problem with my router ?

Thanks

This problem occurs if the hot spot uses Wi-Fi access points or wireless routers that do not support the protocol energy saving 802.11.

It is due also features power management that are included in Windows Vista. Windows Vista by default uses a laptop for the power plan balance. In versions of Windows Vista, the following conditions are true for laptops that are configured to use the Balanced power plan:

• When the laptop is plugged into a power source, the wireless network adapter is configured to use the Maximum Performance mode. This will disable the power saving mode 802.11.
  
• When the laptop runs on battery, the wireless network adapter is configured to use the average energy savings. This has the effect of activating the power saving mode 802.11

you can change the energy saving of wireless network adapter to remedy the situation. Proceed as follows:

• Click Start, click Run, type ncpa.cpl, and then click OK.
• In the Network Connections dialog box, click the right button on the wireless network adapter, and then click Properties.
• Click the Advanced tab, then change the settings for power management. For example, click Power Management in the Property list, drag the cursor to the setting value of power management to use, and then click OK.

make a right click on it => properties => "General" tab, you have "Internet Protocol TCP IP", the point and click in "properties" and there you will see if "Obtain an IP address automatically" is checked, if c is not the case, it will need to check then click OK