invalidtag appears in source view after editing tables

While working with tables in the editor, I noticed that when I paste or delete text into an empty cell the top row moves to the last row. This appears to occur in Chrome 11 on a Mac, Safari and IE 9. When I check the source, the only thing I noticed is the following tags: <invalidtag charset="utf-8"></invalidtag>. I've also noticed that sometimes the table will disappear completely. This doesn't seem to occur with every table that I paste into the editor. The tags appear once I save changes that I've made. I also tested in the demo editor on ckeditor.com site and the same problem occurs. So, I know it's not something with our program since I'm able to replicate it even on the CKeditor site. We only experience this problem with the latest version of the CKEditor which I believe is 3.6.