Windows 7: Wi-Fi connection drops intermittently - only returns after "Troubleshoot connection" resets the adapter

On our laptop (running Windows 7) the Wi-Fi connection drops intermittently.

Symptoms:

Connectivity is suddenly lost, and the "signal strenght" indicator in the tray shows zero strength and a yellow "star" symbol.

What happens then:

• The problem does not resolve itself by just waiting.
• If I click on the tray icon, the "Windows network diagnostics" wizard pops up and tells me that there is a networking problem (duh).
• If I click on the "repair" button (not sure about the wording), the wizard works for a while, then reports that it has reset the network adapter. Then Wi-Fi works again.

While the above procedure has worked every time so far, it is very annoying. It takes 10-20s to repair the connection, and in the meantime downloads, video streams etc. may have been aborted.

Some more details:

• The problem occurs without any apparent regularity, but usually a few minutes after powerup (though not every time). It happens frequently enough to be annoying.
• It is unlikely to be a router problem - another laptop running at the same time usually has no Wi-Fi problems.

I am at a loss about what to try to troubleshoot this. Any ideas?

Computer: Acer Aspire 7739Z. Wi-Fi card: Atheros AR5B125

Edit

Some more details. The network is a simple home network:

• Internet via ADSL from Deutsche Telekom (I'm in Germany)
• ADSL modem/router/WiFi AP combo from Deutsche Telekom (Speedport W723V), using WPA2.
• Only two computers connected, both laptops over WiFi. One shows the problems described, the other (an old Thinkpad running Linux) works fine, even while the other computer is having connection problems.

Disable power management of the wireless adapter. I have seen this kind of flaky behavior before with wired network connections that were under power management by the OS.

1. Open 'Computer Management'

2. Highlight 'Device Manager'

3. Expand 'Network Adapters'

4. Right click the entry for 'Atheros AR5B125' and choose 'Properties'

5. Click the 'Power Management' tab and uncheck all three boxes (especially "Allow the computer to turn off this device ...")

You could download the latest NIC driver from ATHEROS Wireless drivers for Windows. Search for the AR5B125 line and click on the green V sign for your version of Windows 7 (32-bit or 64-bit). Reboot after installation.

If installing the driver does not fix the problem, go into Windows Update and ensure that your computer is fully patched for both important and optional updates. Call Windows Update repeatedly as long as it can find anything to install.

It the problem still persists, it is worthwhile checking if the cause is not hardware. Find an external USB WiFi NIC and try it out. If this fixes the problem, then the built-in NIC is faulty, and the question then arises whether the computer is still under warranty.

A rather long shot is to see if this is caused by an installed application, by booting into Safe mode with network (which is rather painful to use).

A few more questions as food for thought --

Does your network have a security system in place that might be disconnecting you from the network due to suspicious network behavior?

Does your laptop have a firewall that is shutting down the NIC?

Does this happen while moving the laptop between different wireless access poinst?

I saw drivers and software mentioned in this thread, but have you checked the firmware version?

What is your connection strength normally, when you have a good connection? (sometimes even a metal cart or person passing through the area can affect your connection if it is weak)

Is this new behavior, or has this been happening ever since you started using the wireless connection on this laptop?

This might be a problem with the wifi channel you are using. If you have a router that is commonly used (like a fritz box or something like that), then its default channel might be swarmed with connections and interferences. Some routers have a graphical display to show the load of interferences on its channel. I suggest you to set the wifi to a more uncommon channel (like 12 or so) and look if the error persists.