Wireless Connection Loses Internet Access

Here's a peculiar one, methinks!

For the last few days only, I switch the Vista wireless laptop on and it can immediately connect to the Internet thro' my router, as is normal. Then sometime much later on in the evening, without doing anything, indeed while it is idling, it just loses its Internet connection, altho' it is still connected to the router with a local IP addy. Both Ping and Browse somewhere outside time out; they both can connect locally to the router. The Status of the Wireless Connection seems to flip between "Local & Internet Access" and "Local Access Only" but it makes no difference.

However, as soon as I transfer my Ethernet cable from my PC to the laptop, its Internet access is resumed perfectly OK.

I have tried all sorts of things: Reboot router, Change Channel, Reconnect, Diagnose & Repair Connection, Disable/Enable Connection, Release & Renew IP, ...

I'm sure that this started happening last Thurs. when I hardly used the laptop. The only change to it of note was that Windows Update automatically downloaded & installed, without my say-so unlike usually, Windows Update Agent 7.4.7600.226 which I suspect is behind the problem. It will not allow me to uninstall this.

I noticed tonight that while I had the laptop on all afternoon connected to the Internet, it lost connection at exactly 9 PM! (I test by a continuous Ping)

Anybody come across this or have any ideas?

I've seen a similar issue on my Vista laptop; connects fine, and has Internet access for ages then suddenly drops wireless then connects locally only. After a minute or so Internet access is restored.

It doesn't appear to be the laptop (works ok with someone else's wireless router) but also doesn't appear to be my wireless router (an XP-based laptop doesn't suffer the same issue). Not quite sure what to make of it.

It's more of an irritation than a problem, as the connection is restored within a minute or so.

Exact same issue with my new Dell Studio laptop. Eventually I tried to disable the wireless connection and install new drivers for the card. This caused a fault with not being able to enable the connection.

Called Dell and they summised it was a registry fault. So had to reinstall Vista O/S. Bit of a pain but it seems to have fixed both the enabling and connection dropping issues.

Sorry, my fault, I once set a firewall rule to stop my grandson going on late but wasn't careful about the IP addy, and I forgot all about it.