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