I had an instance in the past where my PC crashed and I had to reformat it. Luckily I had all my
OOTP stuff saved on disk, although I lost some games and fights I'd run since the last backup. Even though it wasn't a huge loss it was not a nice experience. Now I'm sure to copy my
OOTP and
TBCB leagues aswell as other important files on my PC to a rewritable CD at least once a week.
Constant backing up is really the only way to go to avoid any problems.