back when i had football manager 06 on the 360 i lost around 5 seasons worth of data due to a corrupt game save - whatever that means. i have never played it since.
I had one of those 15 in 1 Memory Cards for the PS1 where you could switch between each set of 15 blocks, i'd been playing Final Fantasy 7 for about 30+ hours when the card decided to format itself, i was not a happy chappy
It was about 12 months before i decided to play the game again, only that time i used an official memory card.