Is your pst file too big? Or there're something wrong with it.You can try to fix your pst file.A third part repair tool called Advanced Outlook Repair may be helpful.You can download a free demo version at http://www.datanumen.com/aor/aor.exe . I think it is a useful repair tool for you. It is easy to recover your PST file by using its wizard. It is a powerful tool to recover messages, folders and other objects from corrupt or damaged Microsoft Outlook PST files.