warnings on html validation

Hi all,

I am a newbie to FCKeditor, and in general to web development. My father have paid a professional web develper for a customized cms using FCKeditor (version 2.3 beta, i'll have to upgrade) inside a php+mysql framework. Now I have the (for me) overwhelming task to administer it (but i like challenges ). My first problem is that the 4.01 html validation gives me a lot of warnings about the slashes in <br />. I've tried to cancel them by hand in the code by clicking the "source" button, but when saving the page, FCKeditor restores the slashes. I guess the problem is that FCKeditor is thought for writing xhtml 1.0. Could you give me any suggestion?

Thanks in advance, and sorry for my bad English.