Could be a corruption in the view, could be a corruption in the pst-file.
It's hard to say without any details to work with.
Try with scanning your pst-file for errors with scanpst.exe.
See http://www.msoutlook.info/question/77
Are you sure your pst files was all right? if not, 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.
Are you sure your pst files was all right? if not, 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.