Double return changes font

[oldecurb]

In Office 2007 when I do a heading then a double return before I start with more typing the double return changes the heading to another font size and type. If I do the double return v e ry s l o w l y then it doesn't change it. If I double return and the font changes I can get it back to normal by doing a backspace.



However this is all incredibly frustrating!

Can anyone offer a suggestion why a double return should change the font. I can't find a setting anywhere

Thanks in advance