This also happened to me yesterday, I updated to v1.09 yesterday morning then played a little GT5. Then I watched some catch up TV on the PS3 but then when I closed the e4OD (Channel 4 catch up player) I got a blue screen with a lot of code on it...... I closed PS3 down and then thought I'd have a go on GT5 again. It presented me with an error but can't remember what it was something like 8****** (* are numbers but can't remember them). I then had to reset all my settings, wallpaper had reverted to normal PS3 one and I had to login etc.
I tried GT5 again, same error. Took disc out and put it back in and it worked (presumably due to logging into my account). Now I had the start movie and all that rubbish to go through and nothing.....!!! I had a clean garage and 20,000 in credits and it asked me to buy a car. Hmmmmmmmmmmm, I had hundreds of cars and loads of trophies. When I go to my XMB menu I see that GT5 is 53% complete and it also shows my trophies......strange. I also have all of my GT5 photos still in the game and all of my saved replays are there and they work.
Any ideas guys?
Tim.