Windows 7 No sound of other programms when line in is plugged..

[Milos Milin]

Hello everyone. I have next problem. When i plug my guitar in Line in, all other sounds except line in are muted. I have Realtek onboard sound card and im using Windows 7 Ultimate 32bit. I did not experience this problem when i was using Windows XP. Does anybody have solution? I did not experience this problem when i was using Windows XP.