Two hotspots don't appear anymore with a specific Wi-Fi adapter?

Question

Three days ago I accessed two Wi-Fi hotspots I regularly use. The next day I couldn't see/connect to those, but I saw other hotspots listed on available networks, and I could connect to other hotspots.

I plugged in a different Wi-Fi adapter, and I was able to see/connect to those two hotspots I had connected to earlier.

I uninstalled/reinstalled the driver for the first adapter, but I still can't see/connect to those two hotspots. I also tried changing the MAC ID for the adapter. I verified there was a new MAC ID with ipconfig /all after connecting to a different hotspot.

I don't think it's a coincidence that I accessed those two hotspots on the same day, and now that specific card doesn't work with those specific hotspots. Those are the two hotspots I use most, and the adapter that has a better antenna.

Could a virus cause this? I am running Windows XP SP3 with all updates.

Answer 1

What channels are the various APs -- the ones that work as well as the ones that don't -- on? This could have to do with radio regulatory domains.

Let's say you're in the UK, which, like all of Europe (ETSI), allows channels 1-13 in the 2.4GHz band, and the two APs you can't connect to anymore are on channels 12 and 13. Now let's say an American expat just moved in next door and brought his US AP with him. It could be sending beacons tagged with the US country code, but the US (FCC) only allows channels 1-11. So when your one client card wakes up, if it sees your neighbor's AP first, it might think it's in the US and limit itself to channels 1-11, which would keep it from accessing those two APs. It could possibly stay this way until it either gets connected to a properly-configured ETSI AP (on any channel), or until the next sleep/wake.