Fonts squashed in IE9

[akc42]

Can anybody give me any clues as to what the problem shown in the attached picture is.  Someone is editing a post and the drop down lists of fonts is squashed.

From the picture they look like they are too big.

This occurs with one of our users using Win7/IE9  .  I've tried it on my setup without seeing any problem

It works for my user with Firefox.

I have a theme that originally came from the default, but its been separated a long time, so could have diverged.  It only has an index template, all the others come directly from default.