2.4GHz interference with brushless?! HELP!!

[jsr]

I got my first 2.4GHz radio and tried it out today. Right from the start, I get a consistent interference. When I hit the throttle, then start to turn, the throttle goes off on it's own. If I let go of the throttle, the car continues to go until I let go of the steering, then it stops.
I have both the steering servo and ESC wires running together (side by side) into the RX. Is this ok? Is there any special routing I need to prevent this interference? It almost seems like the steering signal is getting into the throttle signal. I was hoping to avoid interference without any special routing by going to 2.4GHz. The ESC is not that far from the RX (about 3") and the RX sits atop the steering servo. I've seen pics of other people with similar spacing and setup.
Any ideas on what's going on?

Thanks for the help.