Missing email content

Can anyone help me with this issue. Outlook Express 6 has sudenly begun to misbehave. All my emails are still in their folders - Inbox, Sent, etc. but the content has vanished.The headings are there and even the attachments which came with them. Any idea what is going on - and how it can be repaired? I will of course need to use a different machine to receive emails or I won't see replies. Any help welcome. Thanks in advance.

Gerry