Try adding the following line to your web part code:
where fileExplorer is the RadFileExplorer control. This has been known to fix problems with the control's layout in MOSS pages. Also, try updating to a more recent build of the RadControls (the current version is 2009.2.701).
If you have not done so already, you will also need to add the following fix for the file explorer's AJAX updates to work OK in MOSS:
|//fix for the ASP.NET AJAX UpdatePanel issue in MOSS
|Page.ClientScript.RegisterStartupScript(Page.GetType(), "AjaxUpdatePanelFix", "_spOriginalFormAction = document.forms.action; _spSuppressFormOnSubmitWrapper=true;", true);
The wrong localization (Common_Rename) can happen if you have an older version of the RadEditor.Dialogs.resx file in your MOSS web site's App_GlobalResources folder. Either delete the old resource files or update them to the RadControls version you are using at the moment.
the Telerik team