I was browsing the stats this morning and saw that there were Race Campaign bits still to do. I thought maybe it had unlocked another grid or something. Well, when I went to check, it turns out that I had lost a load of progress - from around the 22nd of December or so. Basically all the big Phantom tournaments that took me ages to get.
Not sure what happened but yesterday morning was the first time in ages I actually turned the PSP off rather than using sleep and I reckon that's when it must have happened. So it must have stopped autosaving at some point.
So check your autosave is still on before switching off.