My newish Dell laptop does an annoying thing. Whenever you use fast user switching to switch from one user to another it "breaks" the wifi card in some way.

So every time you switch user you need to use the "repair" option on the wifi card properties page to make it work again. I've used fast user switching on all of my XP machines and none of the other had this problem.

Anyone know how to fix it ?

Make sure the wifi adapter is using its latest drivers, and definitely make sure that you are using the Windows utility to manage the wifi connections instead of the card manufacturer's management utility.

It is using the latest drivers and it was using Windows to control wifi settings. Ironically it works marginally better when I let the Intel apps control it.

At least when I do that when you switch user it disconnects the first user and connects the second, with Windows in control both end up without a connection.

Are you using WPA/Enterprise or something (i.e. per-user auth, like RADIUS)? I've never tried to do that with multiple users on XP. Using WEP or basic WPA, once the WiFi is connected, it's connected.

Can you set up the connection on a machine rather than user basis like you can with VPN connections which you need to to if you want to connect to a VPN *before* logging in. i.e. make the connection available for all users?

No, just using WPA-Personal as normal.

Not that I'm aware of and I've never needed to do anything like that on an WinXP machine to get wifi not to disconnect when switching users.

This is all very frustrating, this problem pretty much rules out using this laptop as a shared machine. If I can't leave a long running job like an iTunes sync running and not get it killed as soon as Eryl logs in then it makes it useless as a shared machine.

I'm wondering if it is some Dell oddity, but I don't really want to have to go through the hassle of doing a vanilla XP install just to find out otherwise.

So what model laptop/Intel wifi chipset?

Dell Latitude D630, Intel(R) PRO/Wireless 3945ABG.

Depressingly someone else seemed to have the same issue 2 years ago, with no sign of a solution:

http://www.linksysinfo.org/forums/archive/index.php?t-49368.html

It looks like I might have fixed it. I moved my local wifi network to the top of the "preferred" networks list. There were no networks above it that are visible from here (they are all networks I use elsewhere), but I guess it must have been making it stop and look for those other networks when switching user. Or something like that.

The real fix as you guessed earlier is to wipe clean the crap factory install and do it from scratch without all the junk.

I've always had bizarre problems due to the factory install on Dell machines. My guess is that they try to combine as many different configurations of system and models into a single ghost image.

Be grateful it isn't a Sony laptop anyway with their own custom hardware devices and poorly documented driver install procedures.

Yes, definitely. I can't remember the last time I let a Dell OS install go into production. Luckily Dell ships their plain OS CDs with systems, and provides all the drivers on one page, so it's easy to do your clean reinstall as soon as the machine comes out of the box.

I would normally do that, I didn't this time because when the D630 turned up it was remarkable clean, without all the usual crap installed. Notably it had the same versions of various drivers installed as were current on the vendors sites, rather than the usual set of Dell special versions.

Apart from this issue I have no issues with this Dell install, surprising I know. It looks like this issue isn't a Dell one, there appear to be plenty of people out there with this Intel card in non Dell machines who had, but didn't appear to solve this issue.

True. Except that Windows XP SP2 (but not RTM) supported pretty much everything on my Sony Vaio SRX87P when I repaved it before I handed it to the wife. Which saved some time.

I wouldn't have thought to mention it before, but I typically keep all Wi-Fi profiles disabled. All but for the current one. It just keeps momentary loss of connection from causing havoc.