Thats possibly the most bizarre thing I have ever heard, but it's not the first time I've come across it.
Have you rooted? Sometimes, a bad ROM can do that.
Did you drop it really hard? I've heard my fair share of horror stories, and on more than a few times, I've heard that after some rough trauma, the radio in the phone may cease to function properly.
Did this start after you installed an app? I would suggest uninstalling the last few apps you installed, and see if that helps. I wouldn't go past 10 apps though, unless you installed some like a madman (which I love to do
)
If that didn't help, maybe you should take it to a T-Mobile store, see if they can help you. If they can't, I'm quite sure they can help you make a warranty claim so you can get it replaced or fixed.
Let me know if you get it sorted out.