i'm not able to reproduce the probelm using IE9, i can reproduce using IE 10 though.
The file manager does not directly support IE 10.
In the HEAD of "webasssist/kfm/index.php" you can add this line of code:
<meta http-equiv="x-ua-compatible" content="IE=9" >
to force it to use the IE 9 rendering engine.
You could set this to IE-8 if you want, but I find 9 is working fine.