Outlook 2000 - E-mail body comes as a text attachment

[Mahesh Joshi]

Hello,

Recently, my Outlook has started attaching the body of
any incoming plain text e-mail message as an attachment
to the same e-mail.

The name of attachment is any of the following:-

1. ATT000<some_number>.txt
2. <E-mail subject>.txt

This does not happen with any incoming HTML format mails.
I checked the message format in Tools->Options->Mail
Format tab and saw that it is plain text. I believe this
is for outgoing messages though.

Any pointers please?

TIA,
Mahesh