Component Video Problem with Onkyo SR705

[SlmShdy1]

Okay, so I just got my new receiver and got it all hooked up. I have my cable box going into it through component cables and then an HDMI cable to the TV. It was all working fine at first, but then after about 15 minutes of watching TV, the picture starts to move down and I get these weird blocks of color at the top of my screen. I tried different cables but it still happened. It'll go away if I switch inputs on the receiver but then it just comes back after another 15 minutes of watching TV. The only way I could get around it was to run the cable box directly to my TV and just run audio to the receiver. I wouldn't have a problem with this, but one of the reasons I got a new receiver was to have the convenience of having everything plugged into one component. Any ideas? I hope I don't need to replace my whole receiver.