Are you an Outlook user?  There are some great benefits to using Outlook to manage your emails.  One of the best reasons is that it has a robust organizational feature.  However, the way that Outlook stores your emails in a .pst file is subject to some problems here and there.  The worst thing that can happen is that your .pst file ends up getting corrupted.  This can be a very bad situation.  However there are some great .pst repair tools that can have your computer back up and running in no time.  I suggest that you check out www.pstrepair101.com for more information on some of the best pst repair tools.