I had this problem as well. It was a while a go but I think i tried playing another track and also went and did a few games in Arcade mode and after it worked fine. Are you trying to play Nurburgring in Time-trial?
happened to me trying to do a practice in tt mode for high speed ring. bike was the street ducati 999r. i did three laps, exited picked a different bike (the aforementioned 999r) and went back to hsr, and when it came up, i couldnt control the rider, and it was a replay view. had to completely exit the game to the menu, then went back in and it was fine.