[horde] Menu problems

[Luiz Morte]

Hello list,

We have horde version 3.3 installed. Using IE 8 to access horde, the left menu doesn´t
explode when I click in "Mail" menu.
[ ] Horde |
[+] Mail  | <<== Here doesn´t open using IE8
[-] Organizing
    [+] Address book

We try to put this in apache server "Header set X-UA-Compatible: IE=EmulateIE7", but it
doens't work.

Do you know something that we can change to fix this?
Thanks in advance.
Luiz.
PS:
1. I need to use IE
2. Now,I can't update.