I have already answered you in the support ticket, you have opened. For your convenience, I will paste the answer here too, but lets keep the conversation in the support thread.
I am not able to reproduce the issue on my side. I have tested with the latest version of the Telerik.Web.UI(currently Q3 SP1). Could you confirm that you are using the same version? The cause of the issue might be some custom styles that you have applied to your page. I suggest you try:
- Check whether the issue is reproducible in other browser than IE
- Remove the custom styles from the page and isolate the RadEditor in a simple blank page to verify that the issue comes from the control.
In addition you could try to reproduce the behavior in our online demos.
I reviewed the piece of code you sent - you may not set RenderMode="Classic" to all of the tools. You just need to set it to the RadEditor and so it will be rendered in classic mode.