Strange wireless quirk

I had what I consider an unusual quirk the other day and am curious about your thoughts.

On Sunday my son came over to watch football and brought his own laptop to keep track of his fantasy league. I pulled up my WPA code and figured that would be the end of it. He has some form of Dell with Vista installed.

Now in may area there are about 10 wireless networks that will appear within range to various degrees. All of them are secured.

The dell immediately discovered my network but when we tried to connect we got a message that the network was either out of range or disconnected. (I don't remember the exact error message.) It never got as far as asking for a log in.

As a test I tried random secure networks in the area and every one of them asked for a WEP or WPA. The only one that didn't was mine. (10 feet away and showing as excellent.) I attached an ethernet cable through the router (the modem is in a hard to reach place) and it showed as unplugged. In the end I gave up and he used my old laptop.
While I am in no position to check any possible solutions I am still curious about why this should have happened.

Perhaps it is a router setting that I made and am unaware of. (Netgear WGR614) and I did try unplugging it etc. I did not do a full reset because I did not want to be bothered.