Fields disappearing in folders in Outlook 2007


Outlook version
Outlook 2007
Email Account
Hi - hope that someone can help.

I've noticed that recently when I open up a folder within Outlook 2007 the fields are missing from the view pane. All that remains is the size of the email and the 'sort by header' field; the rest are missing. I know that I can replace the fields with the 'Field Chooser' option, and I can format the columns with the 'Format Columns' option but is there a default way to set the fields that are required?

For info, I have 5 accounts, and all are IMAP

Any help will be gratefully appreciated