I cannot figure out what is going on with my audio.

I am using a iMac with a Tascam US-122 card and an MXL 990 condenser mic into it with a USB cable. I record with Audacity, (the stable version) and I get a moment where the cursor is stuck before it will let me record, and then the recording loops shortly after. It's like "Hey, I want a chees- chees- chees- chees- chees-" ad infinitum.

The weird thing is that the built-in mic does not have this effect. It records normally, but I can't use it for my application. (Theater announcement recording and a video commentary; the mic just isn't good enough)

I would really like to have this work soon. I have opening night for theater next thursday and a commentary due next friday. I'm also hoping to do a Let's Play, but I need the audio to work.

Does anybody have any idea what is going on with this?