Do a system restore to a couple of days back. This happened to me a while back. I know that sinking feeling. All my expansions were corrupted!! Because I had logged off when this happened, TS only had the corrupted file (they save a copy every time you log off, but that is the only copy). I did a system restore to a couple of days before and it worked for me. All I lost was two days of expansions. Since I have 10 years worth of expansions, a couple of days is nothing to lose considering what could have been lost if system restore had not worked. I now save a backup copy on my desktop AND on a flash drive once a week.