Laptop Wireless Switch is not turned on…
Most Windows laptops with built-in wireless have a physical switch which allows them to turn the wireless on and off in order to save battery power.
Resolution: Ensure that the switch is in the on position.
Your Hotspot is using a Wireless Channel which is greater than 11…
In some countries there are regulations which permit to use certain wireless channels. For example in the U.S. only channels 1-11 are permitted. Some network card manufacturers make their wireless network card drivers to work only on those channels.
Resolution #1: Use a Wireless Channel between 1-11. To change the router’s wireless channel, go to the router’s admin panel, then go to Wireless > Basic Settings and change the Wireless Channel to a number between 1-11. Don’t forget to test the hotspot after doing this, because there can be interferences on that channel. Try Channel 1, 6 and 11 first, these are the most compatible ones.
Resolution #2: If you cannot change the Wireless Channel in the router for some reasons, you can suggest your customers who are using Vista to download some updated software from their network manufacturer (search for wireless utility)
For some reason Windows allows you to bridge your connections (wired, IEEE 1394 and wireless) and this will stop your Windows PC from being able to get a valid IP address.
Resolution: From the Network Connections window delete all Network Bridges.
It could be the Wireless adapter driver issue.
Resolution: Upgrade the latest driver. Or use Microsoft Wireless Zero Configuration service. Or use Vista wireless software instead of the manufacturer’s software.
For more Vista+Wireless troubleshooting articles please visit this page.