From distance, router settings, WiFi channel and malware that without a lot of detail it's hard to guess this one. It can even be the adapter.
I carry things like the Netgear WNCE2001 to help sniff this out. But then I'm there to see the setup, distance and all settings. Remember, these are tough to diagnose even on site. Here, you can see your lack of detail.
Sometimes when i first turn on my PC i can't connect to my wireless network and the connection status stays at "identifying". It seems totally random as other times (like right now) it works just fine.
I'm using a Real Tek rtl8191s wlan adapter and a BT Home Hub 3.
I've tried turning the hub off and on multiple times, removing the network in the network and sharing center and then connecting to it from scratch and i've set my adapter settings to "obtain IP address automatically" and it doesn't make any difference as sometimes i still can't connect to the network.
Any help would be appreciated as this is driving me crazy.