Built-In Network Adapter not working

I've had my console for about 3 months and I keep getting disconnected from Xbox Live. Today I got back from work and my console can't even connect to it; and when I try and find my wireless router I get the message "You must plug in your Network Adapter to access Wireless Networks" (or words to that effect). It's a brand new Xbox -- surely it can't be broken already? If so then it's a *bleep*ing joke... I don't want to have to send it off because that's just more hassle for me.

Does anybody know if this is a software problem or a hardware problem?

All of my games work fine offline, but it's very irritating since I use my Xbox for things like Netflix and Youtube...

Edit: I've just done a bit of experimentation and it seems that my Xbox Live works if I stand the Xbox up and not lie it down horizontally... This leads me to believe that the Network Adapter is on the none-ventilated side of the Xbox and is overheating on my desk... Does anybody think this could be the case? My Xbox isn't left on for long periods of time, either. :/