Echo problem!?

My mic is connected to a small interface that plugs into my computer. I've been using Audition with the same microphone (computer and everything) for almost a year now and I've just started having this problem: as soon as I click "aim to record" everything I say into the mic starts echoing back into my headphones making it impossible to record. I figured after a while of not figuring out how to fix this I can just mute my track while I record, and that works, except for my track is always slightly off. It doesn't echo when I'm using my mic for any other program and whenever I turn off "aim to record". I would just like to know how to make this go away.