Phone Reboots and Apps Running in the Background

[nootrak4]

I'm New to Android and the Evo 4G (Touch Pro 2, Mogul, PPC6700, Toshiba Sp2023). So Android is new but not really because i played with my Wifes Hero. Here is my problem. only had it for 2 days now and while im on a call the phone just reboots. I had this happen to me 5 time so far. I haven't called sprint yet because i dont think they will be of any good help but is anyone one having this same problem. i cant tell if is the OTA because i did it about 2hr after i got the phone.

For what ever reason i have a app called Advanced Task Killer Free and every time i open the app it shows me 5 different apps that i didn't open (Amazon MP3, Sprint Navigation, Voice Dialer) Specialy the Sprint Navigation (I HATE THIS APP WITH A PASSION) what is the deal with that. Sorry if this has been discusses before but i looked and didnt see anything.

Thank you