Your apartment complex is likely using multiple APs with the same settings (e.g. SSID, key). The only thing differing between them is the operating channel. Your software is "seeing" both APs, and is showing the weaker one's channel info for a short period. This is probably not what's causing your problem though.
Most times I find that when a computer cannot connect to a network while others can, it's a wifi adapter driver issue, but it might be a wifi security compatibility problem. Please post all details of your computer, including the wifi adapter model if you need further help.
I am sitting in front of two computers. Both have single-band wifi cards. One connects to the internet fine. The other does not. I opened inSSIDer on both computer. They show the same array of wireless networks on the same channels with one exception. The computer that won't connect to the internet shows the network I am trying to connect to at channel 6 for a few second, then it shows it at channel 2 for a half second, then back to 6. The computer that works shows it at channel 6 only. Its a public network run by my apartment complex so I have no info on what kind of router it is, etc.