NEED HELP BAD AT WITS END!

Ok,so i'm using windows 7, reaper 4.10 a intel core duo 2.5 ghz processor,behringer xenyx 1202 fx mixer,behringer uca 222 usb controller and rca inputs on 4gb of ram,and im using the onboard sound from my asus p5g41tm motherboard.When i record in reaper it picks up all the recorded parts including the music and puts them in my newly recorded vocal track.so it ends up sounding like the music is leaking from my headphones into the new vocal track,here's the catch though, it happens even when my headphones are muted and even when they are not plugged in as if to suggest that it's picking up the sound by way of interference.There is also increased "room" noise like interference in all of my vocal tracks.I recorded the same tracks in audacity and the room noise still exists but the music does not bleed into the vocal track.i have no idea what to do.

i cant even read that. please use proper spacing/paragraphs.

The answer I'm pretty sure lies in the mixing panel of your Windows on board sound card, not in REAPER. Find your onboard sound mixer. Right now it is obviously feeding what is being played back into your recorded signal. I don't have the same motherboard as you so I can't be more specific, but there might be a recording option like "What you hear" that you can turn off. In the longer term, when you can afford it, get a USB or firewire sound device ... they have several advantages, but I won't go into that here!