Record buzz

I often bang out a drum loop and go into record mode so I can play some instruments over top of it. For some reason now when I press play start while in record mode, there is a distinct buzz sound evident. It does not happen when the track is stopped and i'm simply playing sounds into the record mode. Once I hit play start (while in record mode), the buzz starts up again. While in the main screen and I press play start, the buzz is not there. I'm using a chord that goes from the two 1/4" jacks to an RCA adapter (I believe it's called) that splices the two together which plugs into the 3.5mm headphone jack on my computer. It has worked in the past wonderfully but now for some reason there is a distinct buzz. And NO it does not have to do with the record gain and main volume knobs. I can't count how many threads I've read where some know-it-all guy says something synonymous with "check your knobs!!" and tosses one of these --> at the end just to show how much he knows…..