problem with instrumental tracking into vocal track

so I set up two tracks, one is an instrumental and another a blank track for a vocal take. I only arm the blank track to record, and do a take, when I go back and solo the vocal, the instrumental has recorded into the vocal track along with the vocal, why is this and how can I eliminate it so that the vocal is only in the track and the instrumental is only on its specified track, is something wrong in my soundcard settings? I am using realtek 97 soundcard on vista basic

Be sure there's no sends / routing on any tracks, that can send signal from one to the other. Also, on some cards, there was a 'record what I hear' switch, that would record everything possible getting sent through the card. Turn that off. I know SB cards had that, but I didn't know if AC97 cards did as well. that's all i got.

Okay I fixed this, I had the soundcard set to stereo mix, once I disables that the tracks didn't automatically blend anymore B

I'm having the same problem, except that when I checked my sound card settings the stereo setting was already turned off, just like you when I try and record my vocals the instrumental plays through.