TYPO3 Core

when using Typo3 from IE and I'm copying a table from excel to typo3 in a page, everything is doing fine, but not until I switch the view to html source view and then switch it back to WYSIWYG view and then get back to html source view...here I found "</col>"keep duplicating in the end of "</col>" and after 6times switching the view I get "</col></col>" and this will get duplicating each time I switch the view. I've tried using Fierefox and the result is quite different, when I'm copying the table, it run well until I save the page. after saving the whole block of <col></col> is not translated and keep showed as a text not as html tag, and sometimes(not everytime) it produce the same problem like in IE but just after I've saved the page

This problem occur in my default installation of typo 1.4.2 with RTE 1.3.7. i've tried to uprade the version of RTE in 1.4.2 and 1.4.3 and the problem still occur.
Do I have mistakes in RTE configuration or this is an unknown bug

(issue imported from #M5031)