Maybe your pst file is broken. Check your pst file and make sure it
isn't broken or too big.You can
try a tool called Advanced Outlook Repair. 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.
Detailed information about Advanced Outlook Repair can be found at
http://www.datanumen.com/aor/
W,D