iPhone 4 - cutting off during calls

[Discomposure]

Okay, I've recently purchased the iPhone 4 and I've noticed that after about 3-4 minutes of being on the phone to someone the phone cuts off like it does when the battery runs out. The battery is fully charged though and it happens everytime! I've tried restoring it, and i've tried the new 4.2 update but still no difference.
Also when I'm texting, or listening to music or playing a game on it, a sign comes up saying the temperature is too hot and the iPhone needs to cool down before I can use it again. Even when it's not too hot!
Any of these problems happening with anyone else and does anyone know if there is something I can do to resolve them?

If not I'll be sending it back to apple, I just wondered if there were any solutions because I don't fancy not having a phone for weeks while I send it off!
Thanks :)

[DreamSeeker]

Try putting a case of the iPhone, if you have not heard. The iPhone 4 had a lot of antenna issues when released mainly when holding it with your finger covering the left side. Maybe your one was a batch that was not fixed. But about the overheating, I'd take it to an Apple Store.

[SamB]

I think you should take it to an apple store i have loads of friends with the iPhone 4 and this does not happen to theirs

[Ender]

mine over heats too, but its no biggy imho..

And about the call dropping, i have an otterbox defender on mine, and have spent hours on the phone.. even when i take the case off now and then.

[SwimTech]

Ive had my iPhone 4 since July and when I first got it it would power off even when it was fully charged. I was gonna say with the dropped calls, it because your holding the attentae in the bottom left corner, but I have never gotten a message about the temperature. What you'll need to do is back up your phone (sync it with itunes on your computer) and then bring it back to the Apple Store. They will take you to the genius bar, and most likely give you a brand new iPhone 4 for free.

[Discomposure]

Thanks guys, yeah I'll take it in to the apple store, or send it off haha :)