HELP! My FM4 game just glitched after getting 'Bucket List' achievement!

Hello everyone,

I just started playing FM4 again after not having played it in a while. I have completed World Tour 1x and I’m now trying to win as many races in the Event List as possible. I haven’t done many of them yet, I’d say about 30-35% I would guess. I just did the '50’s classic race in the first section of the Event List with all the classic race cars. I used the MG A Twin Cam which I modified to C425. When I won the 4th race (out of 5) I suddenly got the ‘Bucket List’ achievement. Right after, the game froze! I turned off my Xbox and restarted it, but now the game freezes after loading the main menu!! Now what do I do?? Has anyone else had this problem?? The cd is not scratched or anything. Is there a way to ‘fix’ this? I don’t want to start all over again because I will lose all my cars and designs that I made and downloaded.
This is not the first time a FM game freezes! It happened with me with FM1 that froze everytime you tried to select the big test track.

Sometimes clearing the cache on your Xbox 360 can clear up a lot of issues. Just be sure and “DO NOT” delete your Forza4 file. Check here: Xbox Support

I just cleared the system cache but it still freezes!! These sort of things happened to me with FM1, FM2 and now FM4!! I don’t want to start all over again, I’ll lose every car I had and it took so much time.

Luculent, don’t clear your system’s cache.
I did that last week and I lost all my game saves on my XBOX on every profile I had.
That means all cars, all progress, all money is lost on all my games.