I'm now fairly sure it's a FPS rate problem. I will try to investigate a way to change that and let you know how I get on.

Many thanks for your assistance,
Philip

Marantz NR1710, 5x Martin Logan Fresco i, BW PV1 sub,, Panasonic TX55GZ950, Sky HD+,Panasonic DP-UB820 Blu-Ray.