Hi,
If your code won't post to tags, attach it to the post.
How are you powering your project at the moment? Off the PC USB?
If so then what ever you have connected to Vin on the nano will not be receiving proper regulated supply.
HC-06 should be connected to 5V, as you have said it will work on 5V.
Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
Tom... 