Can't send email from Excel or Word or Powerpoint

Hi there

For some reason, I can no longer send emails using the send command in any

of Word, XL or PPT. I get error messages in each which are slightly

different but which are:

WORD - Logon failed. You must log on to Microsoft Exchange to access your

address book. Error code: "Unspecified error".

EXCEL - General mail failure. Quit Microsoft Excel, restart the mail system

and try again.

PPT - There was a general failure with the email system and this action

could not be completed.

Windows Live Mail is set as my default email programme and in each case is

opens when I choose 'send' but all I get are the above error messages.

Any help will be gratefully received.

Thanks