OE oddity

[Dunphy]

Greetings,
I recently let a friend use my computer for a few minutes to send some
e-mail and somehow they managed to mess things up somewhat. Whenever I
compose new mail or reply, in the new message box, right down at the
left-hand side, bottom, there are three tabs there (edit, source, preview).
I have tried and tried, but can't figure out what these are, or how to get
rid of them.
Can anyone help me out???
TIA

 

[Unknown]

In the window that appears when sending mail, click format and change to
plain text from 'html'.