As far as I remember they used 2 pieces of music in the Scrubs ads so I'm not sure which one you mean. They were "Good Time" by Leroy and "100 Million Ways" by Nash (Rae & Christian Mix).
Thanks for the suggestions. The peice of music was a stop start kind of tune which they synchronised with the trailer. Each time the music stopped the trailer paused with a scene where maybe something fell or a facial expression.It was most definately on an R&B/Reggae tip. It was E4 not channel 4. I'll try these 2 tunes on Imesh and see how I get on.