Outlook 2003 e-mail doesn't contain text.

I've been trying to resolve this problem for a long time and am getting nowhere with it. I'll appreciate any help you can give me.

I'm using MS XP Pro with Basic Office 2003 and HTML format.

All the e-mail I receive has the senders name, address, subject
and, if sent, an attachment. Some arrive with text, but most don't unless I turn on the 'plain text' switch.

After I send I look into my 'sent' folder...the e-mail is there but without text.

I just reinstalled Office 2003 and the problem improved, a little, but it's still there.

Thanks for the help!