Very good coverage on WRC and other motor sport stuff,BUT,a lot of the time I get poor reception,picture keeps stopping,funny colour lines etc,WHY?? It only is on DAVE other channels are OK :

This may sound obvious, but try rescanning you freeview box; after a few goes it should be okay...

If that doesn't work try Freeview's website and type in your area/postcode to see if it's just your area's reception playing up and which channels you'll have full reception with; I hope this helps... if not I'm sorry that's all I can think of right now.