Here's the situation:
I have 3 PCs at home, all connected to TP Link WR340G WiFi router. My main PC is connected with a cable, the HTPC connects via a WN350GD wireless card, and my wife's notebook connects via its own wireless card. All PCs run Windows 7 and Kaspersky.
Now, I bought a second identical wireless card (WN350GD) for my main PC as I will be changing my ISP soon and the new outlet (and router) will be located in the hall, where I don't want any cables (any more than necessary). So I installed the card in my main PC, installed the drivers and here's the problem. The card will not see (find) any wireless networks. The 5 stepped bars in the tray are grey and crossed with a red X. Mind you, the whole network runs fine, as the other 2 PCs connect to the router OK. Also, my main PC will still connect with cable. But not with the new card. I tried messing around in the network center (I have Polish Win 7 so I may be using imperfect translation of English names of certain functions, pardon me) to no avail. I tried to force connect manually but failed. I tried switching the cards - both work in the HTPC, none works in my main PC. The network center won't show any wireless networks. The system manager show the card all right and says it works fine. Problem solving solves nothing.
I mentioned Kaspersky as TP Link say it will cause problems in this regard - I followed their advice described in FAQ but still no luck. Also, the HTPC didn't have such problem before. I also made sure the zero / automatic network in administrator's tools is on and running.
I've run out of ideas and will appreciate any help!
I managed to solve the problem. All I had to do was to disable "Kaspersky Antivirus NDIS 6 Filter" in the properties of the card. Mind you, not uninstall it - just disable, turn off. Otherwise the system crashes.
Unfortunately, the network speed is lousy, but I guess this has something to do with signal strength. Still, I'm connected.