The built-in wireless for the Thinkpad T400 gave me endless issues on Vista.
Everything works perfectly for a while. Then all of a sudden it doesn't work, and worst of all... nothing I do from the Vista network configuration windows can bring the wireless interface back up.
The ThinkVantage wireless tools don't help either and frequently the applications won't load at all. When this happens, the only fix for me seems to be to reboot the machine.
There is a work-around...
The following settings allowed me to virtually eliminate these issues by making sure the wireless interface never turns off to save power. I'm not sure it's completely necessary to do it in both the Control Panel and the ThinkVantage tools -- it doesn't seem to hurt.
- Go to the Control Panel.
- Make sure you're in Classic View.
- Double-click the Network and Sharing Center icon.
- In the navigation area on the left, click on Manage network connections.
- Make sure the Wireless Network Connection for your Intel(R) Wireless WiFi Link 5100 in enabled.
- Right-click on this connection.
- Select Properties.
- Click the Configure button.
- In the new Properties window, click on the Power Management tab.
- Uncheck Allow the computer to turn off this device to save power.
- Click OK.
Make a similar change in the ThinkVantage tools.
- Click on the Start Menu (bottom-left Windows icon on the taskbar).
- In the Start Search textbox, type access connections.
- Click on the Access Connections item displayed in the Programs menu above the textbox.
- In the Access Connections window, make sure it says Basic in the upper right-hand corner.
- If it says Advanced, click on it. It should now display Basic.
- Click on the Tools tab.
- Click on the Global Settings button.
- Uncheck Allow the wireless LAN radio to be turned off when inactive.
- Click OK.