If I create a table and add some content to one of the cells, when I click on the content and click either the ordered or unordered list buttons, the <td> tag gets replaced the the <ul> or <ol> tag. I was able to replicate this on all browsers I tried using the demo at http://demos.telerik.com/aspnet-ajax/editor/examples/overview/defaultcs.aspx
This is related to http://feedback.telerik.com/Project/108/Feedback/Details/53456-when-trying-to-insert-list-in-a-table-the-list-is-inserted-outside-the-td-tag You can follow that other item as well.