RadEditor display issue (LI)

I have an issue using Telerik RadEditor with IE (not Firefox, not Chrome and not Safari). I think that i have a conflicting css style but i have no idea of wich one (tryed to delete most of the styles). I also tryed to add a ContentEditorArea.css.

How RadEditor displays in IE8 (not very different in IE7) : http://www.skalae.fr/radeditor.jpg

EDIT:

Ok. I'm not sure I have a css conflict. So, here is the Asp.net page:

     <telerik:radeditor runat="server" ID="DetailsPratiques"
        ToolsFile="~/App_Data/RadEditLite.xml"
        SkinID="DefaultSetOfTools" 
        width="95%" 
        Height="300px">
            <CssFiles>
                <telerik:EditorCssFile Value="~/view/assets/EditorContentArea.css" />
            </CssFiles>
              <Tools>
                 <telerik:EditorToolGroup>
                        <telerik:EditorDropDown Name="TranslateTool" Text="<img src='/view/assets/flags/fr.png' alt=''/> Translation Tool"
                            Width="130px" ItemsPerRow="1" PopUpWidth="120px" PopUpHeight="260px">
                            <telerik:EditorDropDownItem Name="<img src='/view/assets/flags/fr.png' alt=''/> French" Value="fr" />
                            <telerik:EditorDropDownItem Name="<img src='/view/assets/flags/en.png' alt=''/> English" Value="en" />
                            <telerik:EditorDropDownItem Name="<img src='/view/assets/flags/es.png' alt=''/> Spanish" Value="es" />
                            <telerik:EditorDropDownItem Name="<img src='/view/assets/flags/de.png' alt=''/> German" Value="de" />
                            <telerik:EditorDropDownItem Name="<img src='/view/assets/flags/it.png' alt=''/> Italian" Value="it" />
                            <telerik:EditorDropDownItem Name="<img src='/view/assets/flags/ru.png' alt=''/> Russian" Value="ru" />
                            <telerik:EditorDropDownItem Name="<img src='/view/assets/flags/pt.png' alt=''/> Portuguese" Value="pt" />
                           开发者_运维技巧 <telerik:EditorDropDownItem Name="<img src='/view/assets/flags/he.png' alt=''/> Hebrew" Value="he" />
                            <telerik:EditorDropDownItem Name="<img src='/view/assets/flags/nl.png' alt=''/> Dutch" Value="nl" />
                            <telerik:EditorDropDownItem Name="<img src='/view/assets/flags/ja.png' alt=''/> Japanese" Value="ja" />
                            <telerik:EditorDropDownItem Name="<img src='/view/assets/flags/bg.png' alt=''/> Bulgarian" Value="bg" />
                            <telerik:EditorDropDownItem Name="<img src='/view/assets/flags/ro.png' alt=''/> Romanian" Value="ro" />
                            <telerik:EditorDropDownItem Name="<img src='/view/assets/flags/uk.png' alt=''/> Ukrainian" Value="uk" />
                            <telerik:EditorDropDownItem Name="<img src='/view/assets/flags/sv.png' alt=''/> Swedish" Value="sv" />
                        </telerik:EditorDropDown>
                        <telerik:EditorTool Name="InsertVideo" Text="Multimedia Content" />
                 </telerik:EditorToolGroup>
              </Tools>
          </telerik:radeditor>

Maybe it's important, this is in an ajax accordion :

                <ajaxToolkit:Accordion 
                ID="accordion1" runat="server" 
                FadeTransitions="false" FramesPerSecond="100" TransitionDuration="50" 
                CssClass="jqtheme" HeaderCssClass="header" ContentCssClass=""
                RequireOpenedPane="True" AutoSize="None">
                <Panes>
                    <ajaxToolkit:AccordionPane ID="panier" runat="server">
                        <Header>
                            <div>
                                <li>Informations principales</li>
                            </div>
                        </Header>
                        <Content>

which is closed.

(thank you for your help and sorry for my english and annoying you with that)

You can always try registering the RadEditor skins manually on the page using the RadStyleSheetManager control:

        <telerik:RadStyleSheetManager ID="radstylesheetmanager1" runat="server">
        <StyleSheets>
            <telerik:StyleSheetReference Assembly="Telerik.Web.UI" Name="Telerik.Web.UI.Skins.Editor.css" />
            <telerik:StyleSheetReference Assembly="Telerik.Web.UI" Name="Telerik.Web.UI.Skins.Default.Editor.Default.css" />
            <telerik:StyleSheetReference Assembly="Telerik.Web.UI" Name="Telerik.Web.UI.Skins.Window.css" />
            <telerik:StyleSheetReference Assembly="Telerik.Web.UI" Name="Telerik.Web.UI.Skins.Default.Window.Default.css" />
        </StyleSheets>
    </telerik:RadStyleSheetManager>

This should fix all skin problems you might experience by showing/hiding the editor, using AJAX requests etc. The only thing you might need to change is the skin name in the stylesheet references above (i.e. replace "Default" with the skin you are using).