Solution : don't use IE ;).

It's bootstrap ....

in adminstyle, line 102, you have some padding (2px) removing it and bootstrap apply: did it better ?

So, why are we using bootstrap?

In my version of IE9, the window is forced into compatibility mode as are most sites using bootstrap.

Added Sam to explain why using bootstrap ;)
OK Sam

We use several bootstrap (YiiBooster to be exact) widgets in the administrative interface.
I chose to always include it so any markup is consistent across the whole interface.

The problem seems to be a lot of overrides done in either the global adminstyle.css or the template adminstyle.css.
In my opinion we should clean up the adminstyle.css files, and after that selectively apply needed css fixes for IE or other browsers.
These fixes should be properly commented so we can quickly decide if they are related to issues we are facing; also please do not copy whole blocks of css attributes; only the attributes we are changing should be in our own css files.

sammousa: the question is:
Why included bootstrap ?

I already say we don't have to include bootstrap, because we already have jquery-ui.

selectjs don't need bootstrap, only need jquery.

Denis
PS: and look at the complete sentence from tony : In my version of IE9, the window is forced into compatibility mode as are most sites using bootstrap.
PS2: bootstrap have some really good idea, but break a lot of website.

Fix committed to 2.05 branch: http://bugs.limesurvey.org/plugin.php?page=Source/view&id=12486

Replaced normal selectbox with Select2 widget.

sammousa : seems langage selector have some problem with utf8 caracters.
I upload a file

I think this is you...
http://snag.gy/jnzUW.jpg

Tried both in IE and Chrome.

I am seeing the same thing as Denis in FF, IE9 and Chrome.

Could you confirm that the following line is correct in your local version?

https://github.com/LimeSurvey/LimeSurvey/blob/2.05/application/views/admin/authentication/login.php#L47

To me it seems weird that those html escaped things are even in your page source..

Yup, that line is correct and I just pulled the project.

Snapshot of the source - http://snag.gy/rln1T.jpg

Think i found it in html_entity_decode documentation:

Encoding to use. If omitted, the default value for this argument is ISO-8859-1 in versions of PHP prior to 5.4.0, and UTF-8 from PHP 5.4.0 onwards.

http://php.net/manual/en/function.html-entity-decode.php

tpartner could you check if supplying the utf8 parameter explicitly solves it for you? -- i only have php5.4.

This does indeed fix it - http://pastebin.com/VBjrBMwL

Fix committed to 2.05 branch: http://bugs.limesurvey.org/plugin.php?page=Source/view&id=12488