This issue is regarding Tiny Mice editor 3.0.. (drupal)
For the bigger font in HTML editor, I have figured out that it is specific to tables in IE. A minor CSS tweak will fix this.

As u can see in Screenshot, When u edit the page, contents inside the Table/editor look big, and when u save and preview the fonts are normal.. (when contents are inside <div> they look normal when they are edited)

I dont know what is causing problem..

The below attached one showing when edited in Tiny Mice Editor
Problem with fonts in Tinymice editor-ie.png

Below screen showing normal preview of the same page
Problem with fonts in Tinymice editor-normal.png

Any solutions??