When you're logged on to Windows, your computer can automatically connect to a preferred network (a network that you've previously connected to) that's in range. Sometimes, your computer will continuously switch between two preferred networks, which can cause temporary interruptions to your connection, or cause your computer to lose its connection entirely.
Here are some reasons why this happens and things you can try to prevent the switching.
Your computer is within range of two preferred networks.
There are two things to try:
Move your computer closer to the router or access point of the network you prefer.
Turn off automatic switching in one or both of the network profiles.
Open Manage Wireless Networks by clicking the Start button , and then clicking Control Panel. In the search box, type wireless, and then click Manage wireless networks.
Right-click the network profile you want to modify, and then click Properties.
Click the Connection tab, clear the Connect to a more preferred network if available check box, and then click OK.
There is interference from other devices.
If you have 802.11b or 802.11g network hardware, it uses the 2.4 gigahertz (GHz) frequency. Other devices that use this frequency include microwave ovens and cordless phones. If you have 802.11a network hardware, it uses the 5 GHz frequency. Some cordless phones also use this frequency. These devices can cause interference between your computer and one network, which might cause the computer to try to switch to another nearby network.
There are two things you can try in this situation:
If any devices like these are near your computer, try turning them off temporarily or moving them farther away.
Change the router or access point settings to use a different wireless channel, or set the channel to be selected automatically if it's set to a fixed channel number. Sometimes one wireless channel is clearer than others. In the United States and Canada, you can use channels 1, 6, and 11. Check the information that came with your access point or router for instructions about setting the wireless signal channel.